Low Molecular Weight Glycoprotein Research Articles

Characterization of the platelet membrane glycoprotein abnormalities in Bernard-Soulier syndrome and comparison with normal by surface-labeling techniques and high-resolution two-dimensional gel electrophoresis.

The platelets from three patients with Bernard-Soulier syndrome have been analyzed by surface-labeling coupled with two-dimensional gel electrophoresis and compared with normals. As well as the previously described absence or deficiency in glycoprotein (GP) Ib(alpha) it could be shown that GP Ib beta and an additional low molecular weight glycoprotein GP17 were not detectable using carbohydrate-labeling methods or deficient to the same extent as the GPIb alpha subunit. In addition, the thrombin cleavable glycoprotein could not be detected using carbohydrate-labeling methods in two patients and was deficient in a third. This finding was confirmed in a fourth patient by one-dimensional gel electrophoresis. Thus, the changes in the membrane of Bernard-Soulier platelets are more complex than previously thought.

Fine structural localization of a new Purkinje cell-specific glycoprotein subunit: immunoelectron microscopical study.

AbstractThe localization of a new low molecular weight glycoprotein subunit in cerebellum was studied with the aid of the indirect immunohistochemical method at the electron microscope level. The specificity of this molecule for Purkinje cells in the rat cerebellum suggested by earlier light microscope studies was confirmed. Immunoperoxidase reaction product indicative of the presence of this glycoprotein was exclusively limited to Purkinje cells, attached to the plasma membrane, membranes of the rough endoplasmic reticulum, the cytoplasmic surface of the nuclear membrane, and on polyribosomes. The antigen was found throughout the whole cell, except for the nucleus, and enabled Purkinje cell processes to be traced in the molecular layer, in the granule cell layer (including the nerve terminals in this layer), and to their axon terminals in the deep nuclei. The fine structural localization is discussed with reference to the known properties of this antigen.

Isolation and partial characterization of a low molecular weight trypsin inhibitor from human urine

A low molecular weight glycoprotein which completely inhibited trypsin at a 1 : 1 molar ratio was isolated from human urine. It was generated from a precursor molecule which in turn derived from plasma inter-α-trypsin inhibitor. It had one polypeptide chain with a molecular weight of about 20 000 and a high content of half-cystine residues. Its amino-terminal amino-acid sequence was Val-Thr-Glu-Val-Thr-X-Leu-Glu-Asp-.

Intracellular protein synthesis and the in vitro translation of coronavirus JHM mRNA.

The genome of the murine coronavirus JHM is a single-stranded, non-seamented RNA with a molecular weight of 5.4 — 6.7 × 10. The genomic RNA is infectious and at least one third is polyadenylated (Lai and Stohlman, 1978; Wege et al., 1978). The virion contains six proteins, four of which are glycosylated (Wege et al., 1979; Siddell et al., 1981b), including high and low molecular weight glycoproteins and a phosphorylated nucleocapsid protein of 60,000 molecular weight (Stohlman and Lai, 1979; Siddell et al., 1981a). Associated with purified virions is a protein kinase activity which specifically phosphorylates pp60 in vitro (Siddell et al., 1981a).KeywordsTranslation ProductRabbit Reticulocyte LysateMouse Hepatitis VirusChase PeriodGeneral VirologyThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Specific biochemical and immunological properties of some water-soluble glycoproteins produced by rat gastric mucosal scrapings in vitro

1. 1. Two major glycoprotein components were released in vitro by rat gastric mucosal cells after 4 hr incubation with radioisotopes: a high molecular weight fraction with the characteristics of a fucomucin and a low molecular weight fraction, the latter having a higher specific radioactivity than the former. 2. 2. Pulse chase experiments indicate that several low and high molecular weight glycoproteins are synthesized simultaneously with no precursor-product relationship between them. 3. 3. Common antigenic determinants, specific to the stomach were found on the 2 fractions, using immunofluorescence, both fractions appeared to be present in the same cells.

Serological and chemical interrelationship of antigens from Leptospira interrogans serovar canicola.

Antigens of the outer envelope from Leptospira interrogans serovar canicola (Hond Utrecht IV) were extracted by 50% (v/v) ethanol or by sodium dodecyl sulphate and serological analysis suggested that they were identical. The "fraction 4" extracted by alkali was found to contain glycoproteins of high (retentate) and low (filtrate) molecular weight; the latter behaved like a hapten in serology and in animal immunization experiments. Antibodies were raised in rabbits against this hapten by conjugating it to bovine albumin fraction V. The antiserum was found to react with both the low molecular weight and high molecular weight glycoproteins. This anti-hapten serum contained little or no whole-cell-agglutinating antibodies. The fraction 4 retentate behaved like a complete antigen in serological and immunization studies. Fraction 4 retentate and the outer envelope preparations were serologically related but they were not identical. Chemical studies revealed similarities between the carbohydrate component of the outer envelope obtained by ethanol extraction and fraction 4. The outer envelope extracted by ethanol, fraction 4 and its low and high molecular weight glycoproteins contained arabinose, rhamnose, fucose, xylose, mannose, galactose, glucose, glucosamine and glucuronic acid. Three unidentified peaks were observed in gas-liquid chromatographic analysis of the O-trimethylsilyl derivatives of methyl glycosides of all these samples and one of these peaks co-eluted with the O-trimethylsilyl derivative of 3-O-methylmannose.

Esterases and glycoproteins in the salivary glands of Anopheles stephensi

Nonspecific esterases of salivary glands of female and male Anopheles stephensi were separated by microdisc electrophoresis and characterized by different substrates, inhibitors, and activators. In addition histochemical investigations were performed on whole glands and gland sections. The salivary glands contained two molecular forms of esterases, the high molecular one being of the C-esterase type (acetylesterase), whereas the lower molecular esterase band showed B- and A-esterase activity. C-esterases were mostly confined to the saliva of the lateral lobes, and the B- and A-esterases to the gland cells. Microdisc electrophoresis of native and SDS-treated gland proteins revealed high concentrations of low molecular weight glycoproteins in the distal portion of the lateral lobes, and a viscous, high molecular weight glycoprotein complex in the secretion of the median lobe. The specific functions of the secretory products are discussed.

Isolation of a low molecular weight glycoprotein inhibitor of calcium phosphate precipitation from the extra-parotid saliva of macaque monkeys

A low molecular weight (9600) glycoprotein was isolated from monkey ( Macaca arctoides) extra-parotid saliva by gel filtration on Sephadex G-200 and Sephadex G-50. Criteria of purity included immunodiffusion, immunoelectrophoresis and polyacrylamide gel electrophoresis. The molecule contained 76 per cent protein, 23.4 per cent carbohydrate and 0.6 per cent phosphorus. The glycoprotein was a potent inhibitor of calcium phosphate precipitation.

Isolation and characterization of glycoproteins from canine tracheal mucus

Three homogeneous glycoproteins were isolated from reduced and S-carboxymethylated canine tracheal pouch mucus by gel filtration and ion-exchange chromatography. Initial fractionation was carried out on Sephadex G-200; chromatography of the excluded Sephadex G-200 fraction on Bio-Gel A-15 m yielded two high molecular weight glycoprotein fractions. Following rechromatography on the same column, the main fraction behaved as an electrophoretically homogeneous high molecular weight (581 600) glycoprotein, with a high carbohydrate content (80%) and a single amino-terminal amino acid (arginine). Ion-exchange chromatography (DEAE-cellulose) of the included Sephadex G-200 fraction yielded two electrophoretically homogeneous glycoproteins of lower molecular weight (20 800 and 24 600, respectively). A single amino-terminal amino acid, glycine and alanine, respectively, was detected for each glycoprotein. Chemical analysis of these three glycoproteins revealed the presence of fucose, galactose, N- acetylgalactosamine , N- acetylglucosamine , N- acetylneuraminic acid and sulfate monoester. The high molecular weight glycoprotein had a higher hexose, sialic acid and sulfate content, per mg of protein, than the low molecular weight glycoproteins. The results of the alkaline borohydride treatment indicated that the majority of the carbohydrate chains of these glycoproteins are linked to the protein core through O-glycosidic bonds involving N- acetylgalactosamine and serine or threonine.

Immunogenetics of a sheep (Ovis aries) serum antigen.

SUMMARYAn allotypic specificity (A1) of sheep serum is described. The antigenic determinant is located on a low molecular weight glycoprotein which has its isoelectric point at pH 5 and is capable of interacting with the lectin concanavalin A.Family studies showed that the allotype is inherited in a simple Mendelian manner.

A theory on the differentiation of bone-marrow stem cells

Differentiation of pluripotent stem cells is viewed in parallel with maturation of lymphoid cells. Both processes share many features each occurring within a reticular framework with its component RE cells. RE cells are seen as providing control over stem cell differentiation in marrow thus minimizing stem cell competition by concentrating differentiation stimuli of a particular kind. The differentiation molecules are considered to be histocompatibility and tissue specific antigen components derived from aging or activated mature blood cells. They are probably low molecular weight glycoproteins. Evidence that histocompatibility antigens are of importance in cellular differentiation is presented. The hypothesis presupposes positive feedback mechanisms to bone-marrow with threshold responses being determined by RE cells.

Incorporation of glycoproteins into peripheral nerve myelin.

Peripheral nerve myelin contains a dominant low molecular weight glycoprotein called Po. To study the metabolism of this glycoprotein, tritiated fucose was injected into the peripheral nerves of adult mice and developing rats, and the temporal distribution of label was examined by autoradiography and gel electrophoresis. Mice and rat pups, injected with fucose, were sacrificed from 1 h to 98 days later. Series of autoradiographs were prepared. At the shortest labeling periods, newly formed product was confined to juxtanuclear Schwann cell cytoplasm, in association with regions rich in Golgi apparatus. After longer labeling periods, silver grain levels in Schwann cell cytoplasm decreased; concomitantly, there was an increase of silver grains associated with myelin. In adult animals, label associated with myelin was concentrated over outer layers of thickly myelinated fibers. Even at the longest time intervals examined (72 and 98 days), this distribution of label was largely retained. In contrast, in developing animals, label became associated with inner layers of the thicker sheaths. At no time was label observed over axons. Gel electrophoresis revealed that tritiated fucose was a suitable precursor for the faster migrating peripheral nerve glycoprotein(s). At all times examined, there was a single major peak of radioactivity that co-migrated on sodium dodecyl sulfate (SDS) acrylamide gels with the Po protein. Sometimes, a faster migrating shoulder of radioactivity was noted. With increased labeling periods, there was an enrichment of radioactivity associated with Po, indicative of a relatively slow turnover rate.

Water binding by antifreeze glycoprotins from Antarctic fish.

Low molecular weight glycoproteins isolated from serum of Antarctic fish have been shown1 to be responsible for freezing point depression which permits survival at temperatures down to −1.9 °C. The principal active antifreeze glycoprotein (AFGP) of several Antarctic species consists of a repeating tripeptide Ala-Thr-Ala with a disaccharide galactosyl-N-acetylgalactosamine linked to the threonine residue2–4. The AFGP is more effective in freezing-point depression on a weight basis than NaCl and several hundredfold more effective than ordinary proteins2. Melting point, however, is virtually unaffected by the AFGP5. We have investigated the possible role of proteinbound water in the unusual antifreeze activity of the AFGP. Ordinary proteins such as bovine serum albumin, haemoglobin, and lysozyme show hydration levels of about 0.4 g H2O per g protein6. This water does not freeze at temperatures down to −35 °C, but is sufficiently mobile to produce a measurable proton magnetic resonance signal. Quantitative determination of the amount of this ‘bound’ water is therefore possible in frozen protein solutions7. We have used this technique to examine water binding by the AFGP over a range of temperatures below the freezing point of bulk water.

A low molecular weight glycoprotein associated with isolated myelin: distinction from myelin proteolipid protein.

Abstract— A low molecular weight glycoprotein has been demonstrated in myelin isolated from immature rat brains. Both short term and long term fucose incorporation studies have identified this protein in the proteolipid protein region of a sodium dodecyl sulfate, polyacrylamide gel. A 1.7‐2.1 fold increase in radioactive fucose in this glycoprotein relative to the major myelin glycoprotein was seen after long term fucose incorporation (21 days) compared to short term incorporation (18–22 h). The demonstration that this fucose‐labelled protein is distinguishable from that of proteolipid protein was achieved by a variety of independent techniques. One technique involved a comparison of ether‐ethanol extracted, freshly isolated, myelin with myelin extracted with chloroform‐methanol. Treatment of isolated myelin with chloroform‐methanol results in the solubilization of the proteolopid protein and its subsequent absence on gel electrophoresis while, in contrast, an enhancement of fucose label was observed in the same region of the polyacrylamide gel. Another procedure involved the electrophoretic separation of the radioactive fucose peak from that of proteolipid protein by employing a continuous, phosphate buffered, gel system. Finally carbohydrate analysis by gas‐liquid chromatography of a partially purified proteolipid protein fraction did not reveal significant amounts of carbohydrates which are characteristic of glycoproteins. The identification of this minor glycoprotein comigrating with proteolipid protein indicates, therefore, a greater complexity associated with the purified myelin membrane than has been previously demonstrated.

The chronically reserpinized rat as a possible animal model for cystic fibrosis. IV. The protein composition of pulmonary lavage fluid.

Lung lavage samples obtained from patients with cystic fibrosis (CF) had significantly higher levels of total protein per ml lavage fluid (0.49 vs. 0.30 mg/ml). A significant increase in the absolute and relative amounts of a low molecular weight glycoprotein (15,000 mol wt) was noted in lavage specimens from CF patients. Reserpine-treated rats also showed a significant increase in the total protein recovered in the lung lavage fluid with a 233% increase in the absolute and relative amounts of a low molecular weight glycoprotein (15,000 mol wt). Thus, reserpine induced changes in the secretions of the lung of the rat which are similar to those observed in samples obtained from the lung of CF patients.

Isolation and partial characterization of a porcine low molecular weight protein occurring in plasma and urine

1. 1. A low molecular weight (LMW) glycoprotein was isolated in the pig from urine produced after the induction of proximal tubular damage and uremia by maleic acid. 2. 2. The purification steps included ultrafiltration, gel chromatography on Sephadex and anion exchange chromatography. 3. 3. The molecular weight, determined by SDS-polyacrylamide electrophoresis was 12,500. The protein appeared heterogeneous in agarose gel electrophoresis. Immunoelectrophoresis and crossed immuno-electrophoresis demonstrated 2 major zones in the α-region, a minor in the early α 1- and one in the β-region. 4. 4. Like the human LMW proteins it appeared in trace amounts in normal plasma and urine but its characteristics were unlike any of the known human plasma LMW proteins.

Specificity of low molecular weight glycoprotein effector of lipid glycosidase

Specificity of low molecular weight glycoprotein effector of lipid glycosidase

Lens glycoproteins: biosynthesis in cultured epithelial cells of bovine lens.

1. Radioactivity from [3H]glucosamine is rapidly incorporated into cellular fractions of lens epithelial cells cultured in vitro. The incorporated isotope appears largely in glycoproteins of the cell surface that are exposed to trypsin and are released into a soluble form by proteolysis of intact cells. Glycoproteins are also secreted by cultured cells and can be recovered in the culture fluids. Sodium dodecysulphate-polyacrylamide gell electrophoresis shows that a range of glycoproteins with apparent molecular weights from approximately 14000 to 120000 are present. The relationships of these glycoproteins to collagen and the non-collagenous glycoproteins of lens basement membranes are discussed. 2. A plasma membrane fraction obtained from non-trypsinised lens epithelial cells contains one major glycoprotein of apparent molecular weight 120000. A major non-glycosylated polypeptide of molecular weight about 38000 detectable by Bloemendal et al. (1972) in plasma membranes of differentiated lens fibre cells was not prominent in lens epithelial cell membranes. 3. Examination of lens basement membranes extracted in various ways failed to reveal major glycoproteins of low molecular weight. Higher molecular weight glycoproteins, some of them related to collagen, were present.

β Trace protein. Purification and urinary excretion studies in selected diseases

β trace, a low molecular weight glycoprotein of unknown biological function has been known for some years to be present in trace amounts in many human tissues. The present work reports purification of β trace protein by a new method and quantitation of this protein by radial immunodiffusion in concentrated urine samples obtained from patients suffering from various diseases, in particular haemopoietic malignancies. Increased levels of β trace protein were found in some but not all cases of paraproteinaemia (myeloma, macroglobulinaemia), leukaemias and lymphomas. Excretion of this protein was found to be related to the filtered load (at the glomerulus). High β trace excretion was not necessarily accompanied by high total urinary protein excretion; no definitive relationship was found between β trace excreted and any parameter of renal function, notably serum or urinary creatinine, serum urea or creatinine clearance. No association could be demonstrated between high β trace excretion and paraprotein concentration in myeloma and macroglobulinaemia, or peripheral white cell count in the leukaemias.

Studies on the structure and activity of low molecular weight glycoproteins from an antarctic fish

Two groups of low molecular weight glycoproteins were isolated from the blood serum of an antarctic fish Trematomus borchgrevinki . The complete structures, both the amino acid sequence and the configuration of the carbohydrate moieties, have been studied. The two glycoproteins are similar in structure but different in size. Solutions of these glycoproteins display a thermal hysteresis similar to that of solutions of larger glycoproteins previously isolated from the same fish.