Concanavalin A-binding Sites Research Articles

Strongyloides ratti: Chemokinesis of glycolytic enzyme- and lectin-treated third-stage infective larvae in vitro

The infective third-stage larvae (L3s) of Strongyloides ratti, a parasitic nematode in rodents, showed two types of chemokinesis on a gradient of sodium chloride (NaCl) in an in vitro agarose tracking assay. The types were a consistent directional avoidance behavior under unfavorable environmental conditions and a reduced avoidance behavior under favorable conditions. We examined the effects of treatments with glycolytic enzymes and lectins by analyzing the avoidance behavior. l-Fucose dehydrogenase, hyaluronidase, β-glucosidase, α-mannosidase, β-galactosidase, concanavalin A, wheat germ agglutinin and soybean agglutinin exhibited inhibitory or enhancive effects on chemokinesis. We also confirmed the sites of the amphids of L3s aside from the mouth at the anterior end by scanning electron microscopy, and that concanavalin A-binding sites existed in the vicinity of the amphids using lectin-histochemistry. The carbohydrate moieties in the amphids of S. ratti L3s may play an important role as chemosensors in perceiving environmental cues.

Influence of aging on candidal growth and adhesion regulatory agents in saliva.

Although oral candidiasis is frequently seen in the elderly, the factors determining candidal growth have insufficiently been explored. Hence, we examined the influence of aging on candidal adhesion and growth-inhibitory agents in saliva in 45 healthy volunteers and 60 patients with oral candidiasis. Both non-stimulated and stimulated salivary flow rates (SFRs) in the healthy controls decreased with aging. A gradual decrease of SFRs with aging was also observed in the patients, and the SFR levels were markedly lower than those in the controls. Although the salivary glucose levels were almost constant in all age groups, secretory immunoglobulin A and lactoferrin levels in saliva were significantly decreased statistically with age, and a marginal age-associated decrease in transferrin levels was also observed. In addition, the generation of superoxide from neutrophils in saliva and their Candida killing activity decreased with age, and these phenomena were more apparent in the patients. Furthermore, a larger number of Candida adhered to oral keratinocytes obtained from the elderly healthy controls than to those obtained from young controls. Correspondingly, keratinocytes from the aged controls showed more concanavalin-A binding sites than those from the young controls. However, oral Candida did not increase with increasing age in the controls, although an age-associated increase of oral Candida was observed in the patients. Taken together, these results indicate that the decreases of SFRs and salivary anti-candidal factors, suppression of salivary neutrophil function and the increase of candidal adhesion sites on keratinocytes predispose elderly individuals to oral candidiasis.

Change of oligosaccharides of rat brain microsomes depending on dietary fatty acids and learning task.

We have analyzed oligosaccharide chains in brain microsomes of rats fed an n-3 polyunsaturated fatty acid-deficient (safflower oil group; S group) or -rich (perilla oil group; P group) diet before and after brightness-discrimination learning tasks. The amount of concanavalin A-binding sites (mainly mannoside) of the brain microsomes was found to be significantly less in the S group than the P group before the learning task. Detailed analysis of glycoprotein glycans demonstrated that high mannose type oligosaccharides were dominant in brain microsomes before the learning task in both dietary groups, whereas multiantennary complex-type oligosaccharides became dominant after the learning task and especially a tetra-antennary glycan, that had a core structure of the glycan of neural cell adhesion molecule, was more increased in the S-group than the P group. When polysialylated glycans were analyzed on serotonin-conjugated HPLC column, the glycans in the S-group microsomes before the learning task contained larger amount of higher affinity-polysialylated glycans to serotonin column than those in the P-group, and also contained larger amount of phosphoglycans that showed also high affinity to serotonin column than the P-group. Removal of mannoside from microsomes by alpha-mannosidase-treatment changed the membrane surface physical property, especially permittivity, as revealed by analysis of the interaction with 1-anilinonaphthalene-8-sulfonate. These results suggest that high mannose content and several multiantennary glycans including polysialylated and phospho-glycans were changed by dietary n-3 fatty acid deficiency and learning task in rat brain microsomal glycoproteins and that these changes may affect membrane functions through changes of membrane surface physical properties and reactivity against serotonin.

Immunochemical analysis of the H and M glycoproteins from Histoplasma capsulatum.

The H and M antigens of Histoplasma capsulatum are glycoproteins, and both possess epitopes found on the C antigen, a cross-reactive galactomannan shared by the major genera of systemic dimorphic fungi. We modified the H and M glycoproteins by chemical and enzymatic digestion to determine the relative contributions of the carbohydrate and protein moieties to the immunological reactivities and the apparent molecular weights of these antigens. Endoglycosidases with known action patterns were used to determine the nature of the glycopeptide bonds in the H and M antigens. The effects of these treatments were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, lectin binding, and enzyme-linked immunoelectrotransfer blots probed with polyclonal and monoclonal antibodies (MAbs). Oxidation with 100 mM periodate destroyed the common fungal epitope recognized by MAb CA1-CB4 and nearly all of the concanavalin A-binding sites on both the H and M antigens; it also caused the molecular mass of the M antigen to shift from 94 to 88 kDa. Treatment of samples with O-glycanase had little, if any, effect on the H and M glycoproteins. On the other hand, treatments with endo-beta-N-acetylglucosaminidase H, and particularly peptide N-glycoproteins F (PNGase F), produced pronounced shifts in the M(r) but did not completely eliminate concanavalin A- or MAb CA1-CB4-binding sites. PNGase F treatment caused the molecular mass of the H antigen to shift from 116 to 94 kDa and that of the M antigen to shift from 94 to 74 kDa. The susceptibilities of the H and M glycoproteins to endo-N-acetyl-beta-D-glucosaminidases suggest that their glycosidic moieties are N linked.(ABSTRACT TRUNCATED AT 250 WORDS)

Postembedment Labeling of Intracellular Concanavalin A-Binding Sites in Freeze-Substituted Fungal Cells

Bourett, T. M., Picollelli, M. A., and Howard, R. J. 1993. Postembedment labeling of intracellular concanavalin A-binding sites in freeze-substituted fungal cells. Experimental Mycology 17, 223-235. We have successfully identified specific intracellular concanavalin A (Con A) binding sites in cells of the fungal rice blast pathogen, Magnaporthe grisea. A postembedding procedure, lectin-gold complex, and freeze-substituted material were used to localize Con A binding within (1) smooth membrane cisternae, (2) the plasmalemma, (3) vesicular and nonvesicular components of the Spitzenkörper exclusive of the core region, (4) the contents of vacuoles distal to the hyphal tip, (5) a population of vesicles in conidia just prior to germination, and (6) the cortical region of cytoplasm in hyphae. These results offer new biochemical information concerning fungal cell physiology, not readily available through other analytical methods, and demonstrate a promising means for the further characterization of the enigmatic endomembrane system in fungi.

Effects of laboratory exposure to sediments contaminated with polycyclic aromatic hydrocarbons on the hemocytes of the American oyster Crassostrea virginica

We have previously shown that hemocytes of American oysters collected from polycyclic aromatic hydrocarbon (PAH)-contaminated areas in the Elizabeth River, Virginia, have a lower ability to phagocytose yeast particles and a decreased expression of concanavalin A-binding sites as compared to hemocytes of oysters collected from cleaner environments. In the present study, we exposed healthy oysters to PAH-contaminated sediments of the Elizabeth River under laboratory conditions for up to 11 weeks. The data obtained indicate that exposure to the contaminated sediments induced a significant suppression in the number of Con A-binding sites as early as four weeks post exposure, but had no significant effects on the phagocytosis. On the other hand, depuration of the Elizabeth River oysters was accompanied by a steady increase in the number of hemocytes expressing Con A and phagocytosis was slightly enhanced. The sum of our data indicates that phenotypic changes are probably more sensitive to PAH exposure than functional parameters.

Extracellular Concanavalin A-binding sites during early interactions between Pinus banksiana and two closely related genotypes of the ectomycorrhizal basidiomycete Laccaria bicolor

Pre-embedding and postembedding methods for labelling Concanavalin A (Con A)-binding sites were compared using five ectomycorrhizal fungi. Extracellular materials were more reliably labelled using the pre-embedding method. The pre-embedding method was therefore used to localize extracellular Con A-binding sites during the initial stages of association between Pinus banksiana and two Laccaria bicolor strains which have different root colonizing abilities. The labelling by Con A-colloidal gold complexes was particularly intensive at the hypha-root interfaces involving the more aggressive root colonizer, while labelling was very weak with the less aggressive strain.

Effects of the sterol demethylase inhibitor, cyproconazole, on hyphal tip cells of Sclerotium rolfsii: III. Cell wall cytochemistry

Hyphae of Sclerotium rolfsii were grown on cyproconazole-amended agar at fungistatic concentrations of 0.1, 0.75, and 1.0 μg/ml, which respectively produced approximately 50, 80, and 95% inhibition of hyphal extension. Hyphal tip cells were prepared for transmission electron microscopy by cryofixation and freeze substitution methods. Cell walls of control and fungicide-treated hyphal tip cells were compared cytochemically using periodic acid-thiocarbohydrazide-silver protein, gold-conjugated lectins, and immunocytochemical staining. Cell walls of both control and fungicide-treated cells reacted positively to periodic acid-thiocarbohydrazide-silver protein staining although the patterns of staining were different. Apical walls of control cells were generally thinner than those in fungicide-treated hyphae. Two distinct cell wall layers were identified in the subapical walls of control hyphae while distinct wall layers were typically not observed in fungicide-treated hyphae. Staining characteristics of abnormal cell wall deposits were variable after periodic acid-thiocarbohydrazide-silver protein stain. In regions of mature cell wall of control hyphal tip cells, wheat germ agglutinin-binding sites were localized along the inner layer of the cell wall. In fungicide-treated hyphae, binding sites for wheat germ agglutinin occurred throughout the cell wall except in electron opaque wall inclusions. Concanavalin A-binding sites were localized along the plasma membranes of both control and cyproconazole-treated hyphae in subapical cell regions. Electron opaque inclusions in abnormal cell wall deposits had affinities for concanavalin A. Immunocytochemical localization of β-1,3 glucans occurred in mature cell walls of control and fungicide-treated cells. No β-1,3 glucans were detected in electron opaque wall inclusions of hyphae exposed to cyproconazole. Alterations in the cell wall are discussed in light of the mode of action of the fungicide and aspects of cell wall deposition.

Trichinella spiralis: Antigenic substances associated with the alimentary tract

Postembedding immunogold and immunoperoxidase staining methods revealed that substances occupying the lumen of the esophagus and the midgut were antigenic for both Wistar rats and humans. Specificity of the alimentary tract-associated antigen was assessed by reacting these substances with a panel of serum pools from patients with non- Trichinella helminth infections, including anisakiasis, paragonimiasis, gnathostomiasis, fascioliasis, dirofilariasis, and trichuriasis. The substances had no, or negligible, cross-reactivity among the serum pools with the only exception of severe trichuriasis serum. Cytochemical staining revealed that the substances are PAS positive and are stained red by azan, and the midgut-occupying substance was equipped with exposed concanavalin A-binding sites. The present data suggest the alimentary tract-associated antigen can be purified by lectin affinity chromatography and may be used as a fairly specific antigen for immunodiagnostic purposes.

Acetylcholine receptors and concanavalin A-binding sites on cultured Xenopus muscle cells: electrophoresis, diffusion, and aggregation.

Using digitally analyzed fluorescence videomicroscopy, we have examined the behavior of acetylcholine receptors and concanavalin A binding sites in response to externally applied electric fields. The distributions of these molecules on cultured Xenopus myoballs were used to test a simple model which assumes that electrophoresis and diffusion are the only important processes involved. The model describes the distribution of concanavalin A sites quite well over a fourfold range of electric field strengths; the results suggest an average diffusion constant of approximately 2.3 X 10(-9) cm2/s. At higher electric field strengths, the asymmetry seen is substantially less than that predicted by the model. Acetylcholine receptors subjected to electric fields show distributions substantially different from those predicted on the basis of simple electrophoresis and diffusion, and evidence a marked tendency to aggregate. Our results suggest that this aggregation is due to lateral migration of surface acetylcholine receptors, and is dependent on surface interactions, rather than the rearrangement of microfilaments or microtubules. The data are consistent with a diffusion-trap mechanism of receptor aggregation, and suggest that the event triggering receptor localization is a local increase in the concentration of acetylcholine receptors, or the electrophoretic concentration of some other molecular species. These observations suggest that, whatever mechanism(s) trigger initial clustering events in vivo, the accumulation of acetylcholine receptors can be substantially enhanced by passive, diffusion-mediated aggregation.

Chitosomes lack concanavalin-A-binding sites

Whether intact or dissociated with digitonin, chitosomes isolated from the fungusMucor rouxii lack the ability to bind concanavalin A. The absence of external or internal concanavalin A-binding sites distinguishes the chitosome membrane no only from plasma membrane but also from membranes of other organelles (endoplasmic reticulum, mitochondrion, vacuole). This differential binding ability was used to partially separate chitosomal chitin synthetase from major membranes in a crude cell-free extract ofM. rouxii.

The distribution of concanavalin A- and cationized ferritin-binding sites on plasma membrane of human platelet and the changes of these sites in cells responding to adenosine diphosphate.

Investigations were carried out to study the distribution of the concanavalin A- and cationized ferritin-binding sites on the plasma membrane of human platelets and to ascertain the changes of these sites in cells stimulated with adenosine diphosphate (ADP) with time as well. The concanavalin A-binding sites of the unwashed fixed platelets were sparsely distributed on the plasma membrane at a distance of up to 80 nm from the outer leaflet of the plasma membrane. The washed unfixed platelets, however, showed a dense distribution within a range of 70 nm from the outer leaflet of the plasma membrane. Changes in the distribution of concanavalin A-binding sites on the plasma membrane of platelets stimulated with ADP were characterized by a marked increase in the number of binding sites and by protrusion up to a distance of 150 nm from the outer leaflet of the plasma membrane 1 minute after the reaction had occurred. The concanavalin-A binding sites may be semicryptic in view of the fact that they were exposed by washing or protruded as a result of the stimulation with ADP. The cationized ferritin binding sites were uniformly distributed with high density on the plasma membrane of the unwashed fixed platelets. In washed unfixed platelets, however, they were sparsely distributed with cluster formation. It is suggested that the glutaraldehyde fixation itself has an effect on the binding of the cationized ferritin particles on the plasma membrane of platelets. The various changes in the concanavalin A-binding sites appearing 1 minute after the reaction with ADP may represent morphological evidence indicating that the platelets have acquired adhesiveness.

Identification and localization of concanavalin A binding sites on isolated postsynaptic densities

Synaptic fractions of decreasing morphological complexity were prepared by phase partitioning of synaptic membranes in an aqueous two-phase polymer system containing increasing concentrations of the neutral detergent n-octylglucoside (OG). The morphology, distribution of concanavalin A binding sites (CABS) and protein and glycoprotein composition of the resultant fractions were examined. The lowest concentration of OG employed (0.5% w/w) gave fractions enriched in relatively intact junctions retaining both pre- and postsynaptic structures. Increasing the detergent concentration resulted in the stepwise solubilization of pre- and postsynaptic structures until purified postsynaptic densities (PSDs) were obtained with 1% (w/w) OG. CABS were generally distributed on all membrane structures present in the 0.5% OG fraction, were restricted to synaptic structures in the fraction obtained with 0.75% OG, and were localized to the convex (outer) surface of purified PSDs. Gel electrophoretic analysis showed that the restriction of CABS to the region of the synapse was associated with a marked increase in the concentration of glycoproteins with apparent molecular weights of 180,000 and 130,000. These glycoproteins were retained, and further concentrated in the purified PSD fraction.

Application of lectin--gold complexes for electron microscopic localization of glycoconjugates on thin sections.

A method is described for the electron microscopic detection of lectin-binding sites in different cellular compartments and extracellular structures that uses thin sections from resin-embedded tissues. Various lectins (Ricinus communis lectin I and II, peanut lectin, Lotus tetragonolobus lectin, Ulex europeus lectin I, Lens culinaris lectin, Helix pomatia lectin, and soybean lectin) were bound to particles of colloidal gold and used for direct staining of thin sections or glycoprotein--gold complexes were prepared and applied in an indirect technique (concanavalin A and horseradish peroxidase--gold complex; wheat germ lectin and ovomucoid--gold complex). The details for preparation of such complexes from 14 nm gold particles are reported. The conditions of tissue processing that gave satisfactory staining results and good fine structure preservation were mild aldehyde fixation without osmification and low temperature embedding with the hydrophilic resin Lowicryl K4M. None of the so-called etching procedures was necessary prior to labeling of Lowicryl K4M thin sections. Examples of the use of this approach for detection of glycoconjugates in the rough endoplasmic reticulum, Golgi apparatus, and mucin of intestinal goblet cells as well as plasma membrane and various intracellular structures of absorptive intestinal and renal tubular cells are shown. A comparison is made with preembedding staining results on Concanavalin A-binding site localization in rat liver which shows that problems of penetration common in such a technique are circumvented by the postembedding approach described here. Concanavalin A-binding sites were not only consistently found in nuclear envelope, rough and smooth endoplasmic reticulum, plasma membranes, and collagen fibers, but also in mitochondria, glycogen, ribosomes, and nucleus. These data and those of a previous investigation (Roth J, Cytochem 31:547, 1983) prove the applicability of this cytochemical technique for postembedding localization of glycoconjugates by light and electron microscopy.

Electron microscope localization of concanavalin a-binding sites in plasma membrane- and endoplasmic reticulum-rich fractions from maize coleoptiles

The binding of concanavalin A (Con A) to plasma membrane(PM)-and endoplasmic reticulum(ER)-rich fractions from etiolated maize coleoptiles has been investigated using sequential treatment with Con A and mannosyl-ferritin (Man-Fer). PM vesicles were shown to be extensively labelled at their outer surface, indicating the presence of available mannosyl and/or glucosyl residues in this fraction. Ferritin particles presented a clustered distribution. No label was observed on control vesicles stained in the presence α-methyl-D-mannoside (αMM). Membranes of the ER-rich fraction appeared largely devoid of ferritin particles. Combining this electron microscope study with procedures which render the interior of the vesicles accessible to the lactin, it was found that whereas no modification in the label of PM vesicles occurred, ER membranes were extensively labelled on their cisternal face. The results are totally in agreement with biochemical data reported in the preceding paper (Hartmann et al., Plant Sci. Lett., 30 (1983) 227) and suggest that PM and ER vesicles retain their orientation after grinding of coleoptile tissue.

Isolation of a Concanavalin A-Binding Glycoprotein from Adult Schistosoma japonicum

The presence of concanavalin A-binding sites on surfaces of Schistosoma mansoni schistosomula (Murrell et al., 1978, Exp. Parasitol. 46: 247-255) and on adult worms (Simpson and Smithers, 1980, Parasitology 81: 1-15) has been shown. Bennett and Seed (1977, J. Parasitol. 63: 250-258) reported the isolation of three distinct, tegumental glycoproteins from S. mansoni adults using lectin affinity chromatography. In the present paper, we describe the isolation and preliminary characterization of a Con A-binding glycoprotein extracted from adult S. japonicum. We obtained lyophilized adult S. japonicum (from infected rabbits) through the World Health Organization Special Programme. Previous reports (Kusel, 1972, Parasitology 65: 55-69; Hayunga et al., 1979, J. Parasitol. 65: 488-496 and 497-506) have shown that the abundance of lipid material in adult schistosomes interferes with protein radiolabeling. Thus we first removed much of the lipid from the lyophilized S. japonicum prior to radioiodination. Approximately 50 mg (dry wt.) of lyophilized worms was suspended in 5 ml chloroform: methanol (2:1) and disrupted in a ground-glass tissue homogenizer. After extraction for 2 hr at room temperature, the mixture was centrifuged at 3,000 g for 30 min and the supernate removed; a second extraction was done overnight at 4 C. The pellet was next resuspended in 1 ml of 0.5% Nonidet P-40 (non-ionic) detergent, incubated for 30 min at 37 C, and centrifuged at 3,000 g for 30 min. The supernate was dialyzed against 0.1 M borate-buffered saline, pH 8.5, then radiolabeled with 0.5 mCi Bolton-Hunter reagent (New England Nuclear, Boston, Massachusetts) as described previously (Hayunga et al., 1979, loc. cit.). After exhaustive dialysis against 0.1 M sodium acetate, pH 6.8, containing 0.5 mM Ca++ and Mn++, an aliquot (= approx. 106 c.p.m.) of labeled S. japonicum protein was applied to a 0.5 x 10-cm column of Con A-Sepharose 4B (Pharmacia, Piscataway, New Jersey) at a flow rate of 0.2 ml/min. After collection of the initial peak, the column was washed thoroughly with 300 ml acetate buffer. Bound material was then eluted with 0.1 M a-methylmannoside in acetate buffer, to yield a single peak. The eluate was chromatographed on an LKB Ampholine column, pH 2.5 to 6.0, or lyophilized and resuspended in tris-glycine buffer containing 2% SDS for polyacrylamide gel electrophoresis. The SDS polyacrylamide gel electrophoresis, under both reducing and nonreducing conditions revealed the presence of one major peak, indicating a single moiety, with an approximate molecular weight of 130,000 (Fig. 1A). However, caution is in order when ascribing molecular weights to large glycoproteins separated by gel electrophoresis, because the carbohydrate components of these molecules may induce abnormalities of migration. Ampholine isoelectricfocusing (Fig. 1B) revealed two fractions with approximate pI values of 2.9 and 4.0. When each of the fractions isolated from the ampholine column was analyzed by SDS-PAGE, it was found that the major fraction (pI = 4.0) yielded the single peak (m.w. = 130,000) shown in Figure 1A. The smaller fraction (pI = 2.9) was comprised, for the most part, of low molecular weight contamination. These results extend previous observations about Con A-binding sites on schistosomes. Bennett and Seed (1977, loc. cit.) originally reported the isolation of three surface glycoproteins from adult S. mansoni reacting with Con A. Using slightly different methods for harvesting tegumental material, we have recovered a major, Con A-binding glycoprotein (m.w. = 58,000; pI = 4.8) and some minor peaks, all of which may correspond to those reported by Bennett and Seed. The major gly-

In situ distribution of concanavalin A-binding sites in mesenchyme blastulae and early gastrulae of the sea urchin Lytechinus pictus

The spatial distribution of concanavalin A (conA)-binding sites was studied in situ in order to investigate the role of conA-binding sites in primary mesenchyme cell migration in mesenchyme blastulae and early gastrulae (gastrulation one-quarter complete) of the sea urchin, Lytechinus pictus. In normally developed embryos conA is bound around the entire basal surface of the ectoderm and to the entire surface of ingressed primary mesenchyme cells in mesenchyme blastulae. However, in early gastrulae conA-binding sites are lost on the vegetal half ectoderm and on the primary mesenchyme cells, which had returned to the vegetal half in order to aggregate for spicule formation. ConA-binding is completely inhibited in embryos incubated with α- d-mannoside, but not in those incubated with β- d-mannoside or galactose. In sulfate-deprived embryos conA-binding sites are distributed normally in spite of the deficiency in primary mesenchyme cell migration. In embryos treated with LiCl, on the other hand, the ingressed primary mesenchyme cells migrate extensively, but fail to return to the vegetal half. In these embryos the conA-binding sites on the basal surface of the vegetal half ectoderm remain even at the early gastrula stage. The results correlate the spatial distribution of conA-binding sites with the pattern of primary mesenchyme cell migration in the blastocoel.

Concanavalin A-Binding Sites on the Clonal Muscle Cell Line, L6

Localization and properties of concanavalin A-binding sites (CABS) on the cells of the clonal muscle cell, L6 were investigated by two methods. Using fluorescent concanavalin A (Con A), only occasionally could even faint fluorescence be detected on myoblasts in young cultures. As proli-feration proceeded, the intensity of fluorescence increased and became localized on the boundaries where the cells came into contact with each other. This distribution was not affected by the treatment with EGTA, triton X-100 or colchicine, suggesting that neither the Ca2+, lipid matrix nor the microtubule contributed to the maintenance of the distribution. Cytochalasin B (CB), however, caused the CABS to rearrange as well as morphological changes in the cells. Using Con A and hemocyanin, very low CABS densities were found on young myoblasts. In contrast to the results with fluorescent Con A, dense labelling was found on over the entire cell surface of myoblasts in confluent cultures. Many myotubes had CABS but densities varied from cell to cell. The effects of CB in localizing CABS were also observed by the hemocyanin method which demonstrated that most CABS on L6 cells were affected directly and/or indirectly by CB.

Ultrastructural localization of concanavalin A-binding sites in satellite cells of human skeletal muscle.

Electron-microscopic cytochemical studies on satellite cells of normal human skeletal muscle were carried out using the concanavalin A-peroxidase (Con A-HRP) coupling method. Con A-binding sites, which probably correspond to glycoproteins, were found to be associated with the cell surface, smooth surfaced vesicles, nuclear envelope and endoplasmic reticulum of the satellite cells and were also identified at the cell surface of the adjacent muscle fiber. The possible relationships of these observations to the functions of satellite cells are discussed.

Restriction of patching of bound concanavalin A after incorporation of arachidonic acid into the plasma membrane of virally transformed fibroblasts.

Topographical distribution of concanavalin A binding sites (CABS) was studied in two lines of virally transformed fibroblasts as a function of fatty acid composition. Fatty acid composition was manipulated by incubating cells in fatty acid, ATP, CoA, and delipidated fetal calf serum (FCS). VLM cells grown in medium containing 5% FCS have a clustered CABS distribution. Plasma membrane vesicles (PMVs) derived from these cells have an arachidonate content of 1.7%. Elevation of PMV arachidonate to 15.8% results in a marked restriction of CABS patching, while elevation to 6.8% is associated with intermediate restriction of patching. Restriction of patching is associated with increased microviscosity. CABS of Rous sarcoma virus-transformed chicken embryo fibroblasts (RSV-CEF) are also responsive to arachidonate enrichment medium. Whereas untreated cells have a clustered CABS distribution, cells incubated for 24 h in arachidonate enrichment medium have predominantly a dispersed CABS distribution. In both VLM cells and RSV-CEF, ATP, CoA, and delipidated FCS alone have no effect upon CABS mobility. Inhibition of CABS patching is also observed when aspirin is included in the arachidonate enrichment medium but not when the cells are incubated in prostaglandins, thus suggesting that the restriction of CABS mobility is not mediated by prostaglandins. Other fatty acids (palmitate, oleate, nonadecanoate) failed to restrict CABS movement. The inhibition of CABS mobility is independent of cell shape change.