Vicia Graminea Lectin Research Articles

Clinical utility of plasma membrane vesicles expressing recombinant glycophorin A-encoded blood group antigens.

Although the genes encoding most of the major blood group determinants are now cloned, recombinant blood group antigens are not commonly used in the clinical laboratory. This study assessed the feasibility of using plasma membrane vesicles expressing recombinant glycophorin A blood group antigens as soluble immunoadsorbants. Chinese hamster ovary cells were transfected with plasmids containing the cDNA encoding the M- or N-allele of glycophorin A. Plasma membrane vesicles were chemically induced from stable, high-expressing cell lines. Antibodies were assessed for reactivity in hemagglutination-inhibition assays. Eight anti-M antibodies were evaluated. Vesicles expressing the M-allele of glycophorin A neutralized four antibodies (two murine monoclonals; two human sera), while the activity of four human sera was unaffected. Three anti-N reagents were also evaluated (murine monoclonal antibody; rabbit polyclonal antibody; Vicia graminea lectin). All were neutralized by vesicles expressing the N-allele of glycophorin A. There was no detectable neutralization of other clinically significant blood group antibodies. Plasma membrane vesicles expressing recombinant glycophorin blood group determinants may prove to be useful reagents in the clinical laboratory. However, the partial failure of M antibody recognition requires further study. This general approach could be utilized for any similarly expressed recombinant blood group antigen.

Presence of Vicia graminea lectin- and Vicia unijuga lectin-binding (Vgu) glycoproteins in human fetal membranes and some of their biochemical properties

We have previously reported that Vicia graminea lectin (VGA)- and Vicia unijuga lectin (VUA)-binding glycoproteins (Vgu glycoproteins), malignant tumor-associated antigens, exist in human meconium and amniotic fluid. To examine the origin of Vgu glycoprotein, their presence, some of their chemical and serological properties and their biosynthesis in the human fetal membrane, amnion and chorion laeve and accompanying membrane cells were examined. Perchloric acid-soluble fractions were prepared from human amnion and chorion laeve, after which VUA-binding components (Vgu glycoproteins) were separated by HPLC and affinity chromatography using immobilized VUA. Biosynthesis of the antigens in primary cultured cells prepared from the amnion and chorion laeve were examined by pulse-labeling and immunoprecipitation using immobilized VUA and compared with those in cultured human cancer cells. The results indicated that the serological properties of VUA-binding components in fetal membranes were similar to those of meconium and amniotic fluid, that many molecular species of VUA-binding components were synthesized in amnion and chorion laeve cells and that about 40–50% of antigens synthesized are secreted from cells while antigens synthesized in cultured cancer cells human were hardly secreted with more than 95% of the antigens remaining in the cells. From these results, we concluded that a large part of Vgu glycoproteins found in amniotic fluid is synthesized in cells of the amnion and chorion laeve and secreted into the fluid, and that Vgu glycoproteins synthesized in cancer cells were not secreted, rather they were retained in the cells.

Presence of vicia graminea lectin- and vicia unijuga lectin-binding (Vgu) glycoprotein in human amniotic fluid and some of its chemical and serological properties

Vicia graminea- and Vicia unijuga-binding glycoprotein (Vgu glycoprotein) has been reported as a malignant tumor-associated antigen, which is found in various kinds of malignant tumor-tissues and ascitic and cyst fluids of malignant tumor patients, but not found in 20 kinds of normal human tissues. The glycoprotein reacts with anti-N lectins of Vicia graminea (VGA) and Vicia unijuga (VUA), but does not react with anti-blood group M and N sera. The existence of Vgu glycoprotein in human amniotic fluid is reported here. A perchloric acid-soluble glycoprotein fraction (PASF) was prepared from human amniotic fluid (AF-PASF). Sialoglycoprotein was then separated from AF-PASF by consecutive gel filtration on Sephacryl S-300, HPLC on Asahipak GS-710 and affinity chromatography in VUA-conjugated formyl-cellulofine columns. The sialoglycoprotein with 9.6% (w/w) carbohydrate content showed a molecular mass of 2940 kDa estimated by HPLC gel filtration. The sialoglycoprotein showed reactivity with VGA and VUA, but did not react with anti-M and -N sera. In addition, the sialoglycoprotein reacted with lectins of Ulex europeus, Arachis hypogaea, Maclura pomifera, Canavalia ensiformis, Ricinus communis, Phaseolus vulgaris, Sambucus nigra and Sophora japonica. These results show that Vgu glycoprotein exists in human amniotic fluid, and that Vgu glycoprotein obtained from human amniotic fluid has a similar serological property to Vgu glycoproteins found in malignant tumor-tissues, but its chemical property is significantly different from that of malignant-tumor associated Vgu glycoproteins.

Presence of Vicia graminea lectin- or Vicia unijuga lectin-binding (Vgu) glycoproteins, Vgu glycoproteins with Thomsen-Friedenreich (T) activity and T-active glycoproteins in human meconium

Perchloric acid-soluble fraction prepared from a mixture of meconiums of 22 newborn babies was subjected to a systematic affinity chromatography using Vicia unijuga lectin-Cellulofine column and Arachis hypogaea lectin-Agarose column and separated into four fractions, Vgu glycoprotein, Vgu glycoprotein with T activity, T-active glycoprotein and another glycoprotein fractions. HPLC analysis showed that the first fraction contained three glycoproteins with molecular weight (M w) of about 19,400 kDa, 5500 kDa and 1900 kDa, the second fraction consisted of two glycoproteins with M w of about 460 kDa and 150 kDa and the third fraction composed of several glycoproteins including the main glycoprotein with M 2 of about 11,700 kDa.

Serological property of perchloric acid-soluble glycoprotein fractions of human meconium

Perchloric acid-soluble fractions (PASFs) were separated, in yields of 87.0-151.9 mg per 1.0 g of wet meconium sample, from six samples of human meconium, and identified as glycoproteins having 41.2-74.1% carbohydrate by chemical composition analysis. Six PASFs reacted with anti-A, -B, -Lea and -Leb sera, but did not react with anti-M and -N sera. These PASFs alos reacted with many lectins such as DBA, UEA-I, Vicia graminea lectin (VGA), Vicia unijuga lectin (VUA), Con A, WGA, RCA-I, PHA-E, SBA, SJA, and influenza A and B viruses. The serological results show that six PASFs contained VGA or VUA-binding (Vgu) glycoproteins as new oncofetal substances, but did not contain M and N blood group substances.

Vicia graminea lectin or Vicia unijuga lectin-binding (Vgu) glycoproteins as new tumor-associated substances

The purification and serological and chemical properties of Vicia graminea lectin (VGA) and Vicia unijuga lectin (VUA) were described, and then the binding-specificity of anti-M and -N antibodies and both the lectins was discussed in this review. On the basis of the facts that Vgu glycoproteins which react with either VGA or VUA but not with anti-M and -N antibodies and were not detected in human normal organ tissues and sera, were separated and identified as mucin-type glycoproteins with very high molecular weights from human cancerous organ tissues, ascitic fluids of cancer patients and cyst fluids of human ovarian cystadenoma in malignant, it was concluded that Vgu glycoproteins are new tumor-associated substances.

Isolation and characterization of a Vicia graminea and Vicia unijuga lectins-binding (Vgu) glycoprotein with thomsen-friedenreich (T) activity from human liver metastases of pancreas carcinoma

1. 1. Perchloric acid-soluble fraction from liver metastases of pancreas carcinoma of a patient with blood group B, was subjected to a systematic affinity chromatography using Vicia unijuga lectin (VUA) and Arachis hypogaea anti-T lectin (PNA) as immobilized ligands and separated into three fractions, B-active glycoprotein fraction, serologically inactive glycoprotein fraction and glycoprotein (VP) fraction exhibiting reactivities for Vicia graminea lectin (VGA), VUA and PNA. 2. 2. VGA- and VUA-binding (Vgu) glycoprotein with Thomsen-Friedenreich (T) activity which was isolated, in a high state of purity, from VP fraction by HPLC using Asahipak GS-710 column, was demonstrated to be a mannose-rich glycoprotein with mol. wt of 1492 kDa and contained 40.40% carbohydrate.

Vicia graminea lectin- or vicia unijuga lectin-binding (Vgu) glycoproteins as new oncofetal antigens

Vicia graminea lectin- or vicia unijuga lectin-binding (Vgu) glycoproteins as new oncofetal antigens

Enhanced reaction with Vicia graminea lectin and exposed terminal N-acetyl-D-glucosaminyl residues on a sample of human red cells with Hb M-Hyde Park.

A sample of polyagglutinable red cells was obtained from a healthy individual (group O, N) possessing a hemoglobin (Hb) variant called Hb M-Hyde Park. The sialic acid content of the individual's red cells is 90 percent of normal, and his cells are agglutinated by monoclonal but not lectin anti-Tn, a panel of lectins specific for N-acetylgalactosamine (or galactose), and N-acetylglucosamine. Enhanced agglutination reactions were obtained with Vicia graminea, Ulex europaeus, and human anti-I and -i. Using various enzyme treatments and different methods of labeling cell surface components, two defective cell membrane sites have been identified: one associated with the O-linked oligosaccharides on sialoglycoproteins and the other associated with exposed N-acetylglucosaminyl residues located on membrane components of apparent molecular weights 88,000 to 130,000 and 46,000 to 73,000 (probably the Band 3 and Band 4.5 regions, respectively).

A new test useful in identifying red cells with a (delta-alpha) hybrid sialoglycoprotein.

St(a+) and Dantu+ red cells (RBCs), treated with 0.1 percent ficin solutions, reacted strongly with Vicia graminea lectin (anti-NVg). No other RBC sample tested gave these results. This test (ficin-pretreated RBCs tested with anti-NVg [FT-NVg]) was used to screen the RBCs of 300 Oriental and 100 black donors. Three percent of the Oriental donor samples tested were FT-NVg+, whereas no FT-NVg + RBCs were found in the black donor samples tested. The FT-NVg test is easy to perform and gives selective reactions with antigens associated with (delta-alpha) hybrid sialoglycoproteins, such as Sta and Dantu. This test can be used for mass screening of RBCs in a search for St(a+) or Dantu+ RBCs. Another application of the FT-NVg test would be to screen RBCs suspected of having a low-incidence antigen before using scarce anti-Sta and -Dantu reagents.

Preliminary investigation of the structure of the carbohydrate component of Vicia graminea lectin, a plant glycoprotein

Purified Vicia graminea lectin, isolated from seeds, was found to contain d-mannose, 2-acetamido-2-deoxy- d-glucose, l-fucose, d-galactose, and d-xylose in the molar ratios ∼3.9:1.5:1.2:1.1:1.0. The oligosaccharides, obtained after hydrazinolysis of Vg-lectin, were N-reacetylated, reduced with sodium borohydride, and fractionated into two peaks. The first peak contained d-galactose, d-mannose, 2-acetamido-2-deoxy- d-glucose, and 2-acetamido-2-deoxy- d-glucitol in the molar ratios 6:3:2:0.7. After h.p.l.c. fractionation into five oligosaccharides, the second peak contained d-mannose, d-xylose, l-fucose, 2-acetamido-2-deoxy- d-glucose, and 2-acetamido-2-deoxy- d-glucitol. Methylation analysis suggested the following general structure for these oligosaccharides: ▪

Effect of pH on the binding of Vicia graminea lectin to erythrocytes. Dependence on the chemical character of red-cell receptors.

Binding of the radioactive Vicia graminea lectin to human blood-group M and N erythrocytes and to horse erythrocytes was studied at pH 6-10. Binding of the lectin to untreated human erythrocytes and to those treated with Vibrio cholerae neuraminidase increased severalfold from pH 6 to pH 8 and was maintained at the maximal level up to pH 9/9.5. On the other hand, interaction of V. graminea lectin with native or desialylated horse erythrocytes was not significantly affected by pH and small differences in the binding were opposite to those found with human erythrocytes: the binding decreased when pH increased from 6 to 9.5. Binding of the lectin to all erythrocytes tested at pH 10 was lowered to about 80% of the maximal values. The differences in pH dependence of V. graminea lectin binding to human and horse erythrocytes most probably resulted from the presence of amino groups in human red-cell receptors and their absence from receptors of horse erythrocytes. The earlier data on the enhancing effect of amino group modification on the interaction of human red-cell glycopeptides with V. graminea lectin support the conclusion that an increase in the lectin binding to human erythrocytes at pH 6-8 is confined to the decreased protonization of the receptor amino groups. V. graminea lectin was irreversibly inactivated at pH 3 and was inactivated by EDTA at pH 7.4 and reactivated by Ca2+ or Mn2+. This suggested that the lectin is a metaloprotein, requiring bivalent cations for the full binding activity. Some quantitative differences between the binding properties of V. graminea lectin, prepared from different batches of seeds, are reported.

Miltenberger Class I and II erythrocytes carry a variant of glycophorin A.

The membranes from Miltenberger Class I (Mi I) and II (Mi II) erythrocytes, two rare variants at the blood group MNSs locus, exhibited an abnormal glycoprotein of 32 kDa apparent molecular mass sharply stained by the periodic acid/Schiff procedure and a decreased content of glycoprotein alpha (synonym glycophorin A, glycoprotein MN) as seen on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Purified 125I-labelled Vicia graminea lectin binds to the unusual 32 kDa glycoprotein separated from Mi I and Mi II erythrocyte membrane of blood group NN or MN, but no significant labelling of this band was observed with Mi samples typed MM. On the basis of such lectin-labelling experiments we have described two heterozygous MN, Mi I individuals that carry one copy of an M gene producing a normal alpha-glycoprotein with M-specificity and one copy of a MiI gene producing a 32 kDa glycoprotein with N-specificity. Further investigations have shown that the 32 kDa glycoprotein was immunoprecipitated by two mouse monoclonal antibodies (R18 and R10) reacting specifically with the external domain of glycoprotein alpha. These results demonstrate that Mi I and Mi II erythrocytes carry an unusual variant of glycoprotein alpha.

Membrane receptors for Vicia graminea anti-N lectin and its binding to native and neuraminidase-treated human erythrocytes

Membrane receptors for Vicia graminea (Vg) lectin on human red cells were analyzed using deoxycholate lysates obtained from 125I-erythrocyte membranes incubated with a purified lectin immobilized on Sepharose 4B. The glycoproteins (GP) specifically bound to the gel were eluted and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Using native erythrocytes the results obtained demonstrate that N red cells have exposed Vg receptors located on GPα (synonym glycophorin A) and GPδ (synonym glycophorin B) whereas on M erythrocytes the Vg receptors are restricted to GPδ. The presence of Vg receptors was also found on the hybrid glycoprotein (made of the N-ter of GPδ and C-ter of GPα) carried by St(a+) erythrocytes. A similar amount of radioactivity was bound to Vg-Sepharose incubated with neuraminidase-treated N or M membranes. The material eluted was tentatively identified as asialo GPα and asialo GPδ, suggesting that numerous receptors have been uncovered mainly on asialo GPα species from M erythrocytes. No glycoprotein component could be identified from the material eluted from Vg Sepharose incubated with native or neuraminidase-treated membrane from a Tn(+) individual. Scatchard plot analysis obtained from binding experiments at equilibrium with M, N, and St(a+) cells revealed the existence of at least two classes of receptors both on native and neuraminidase-treated erythrocytes. Desialylation of the M, N, and St(a+) erythrocytes resulted in an increase in the number of low- and high-affinity binding sites but had no significant effect on the association constants. However, high-affinity binding constants were about six times higher with N (7.07 × 10 7 and 6.61 × 10 7 m −1 for native and neuraminidase-treated N cells, respectively) as compared to M erythrocytes (1.13 × 10 7 and 1.17 × 10 7 m −1 for native and neuraminidase-treated M cells, respectively) whereas the low-affinity binding constants were similar for all types of cells (in the range of 0.1 to 0.3 × 10 7 m −1). The number of Vg binding sites increases from 0.085 × 10 5 to 0.8 × 10 5 (high affinity) and from 2.10 × 10 5 to 6.25 × 10 5 (low affinity) per native and neuraminidase-treated N cell, respectively. On native and neuraminidase-treated M cells the number of Vg receptors increases from 0.011 × 10 5 to 0.51 × 10 5 (high affinity) and 0.13 × 10 5 (low affinity), respectively. The large increase in the number of Vg receptors on neuraminidase-treated M cells is correlated with a large increase in agglutinability. Under similar treatment St(a+) cells behave like N erythrocytes whereas only 0.16 × 10 5 Vg receptors of low affinity could be detected on neuraminidase-treated Tn erythrocytes. The results demonstrate that sialic acid is not required for binding and favor the view that the binding site of V. graminea lectin accommodates with two types of erythrocyte membrane receptors, one including both a contribution of polypeptide and oligosaccharide chains and a second which involves a simple interaction with sugar sequence Galβ1–3GalNAc available only when sialic acids are removed. The latter disaccharide is recognized by the Arachis hypogea lectin which therefore inhibits further binding of the V. graminea to neuraminidase-treated erythrocytes.

Another MNSs variant producing a hybrid MNSs sialoglycoprotein

Summary The red cells of a propositus, A.G., and those of her compatible sister, A.C., were M+N−S+s− but, after trypsin treatment, they failed to react with Vicia graminea lectin. The phenotype of A.G. closely resembled that of J.R. [17], except that the cells of both A.G. and A.C. were agglutinated very weakly by an anti-Hil serum. All three were Wr(a−b−) but reacted with sera from En(a−) propositi. By inhibition tests with soluble MN-SGP extracts and by using protease treated cells A.G. and A.C. cells were shown to lack the ficin resistant Ena antigen (EnaFR) but to have the ficin and trypsin sensitive antigens (EnaFS and EnaTS). The serum of A.G. contained two atypical antibodies, anti-Wrb and anti-EnaFR. SDS-PAGE with subsequent PAS staining showed that A.G. cells lack normal MN-SGP (α) and Ss-SGP (δ) but contained two abnormal components: a hybrid SGP molecule comprised of a portion of MN-SGP and a portion of Ss-SGP (α-δ)A.G., and its dimer (α-δ)2A.G.. The sialic acid content of A.G. cells was about 60% of that normal cells.

Vicia graminea lectin binding to human M and N erythrocytes

The mode of binding of Vicia graminea 125I-labelled lectin to human M and N erythrocytes at 4°C has been investigated. The labelled lectin retained the full activity of native lectin. Lectin association at 4°C was characterized by a t 1 2 of 3 to 5 min, reaching steady-state within 15 min. Incubation of cells for 15 min at 4°C with increasing concentrations of Vicia graminea 125I-labelled lectin showed that saturation binding occurred. Scatchard analysis of equilibrium data determined over a wide range of lectin concentrations yielded a curvilinear plot with an upward concave slope; this representation indicated that there was not a single homogeneous class of noninteracting binding sites. This result could indicate two or more independent classes of binding sites or one class of interacting sites exhibiting negative cooperativity. Since unlabelled lectin, which at the concentration used, rapidly binds to available receptors, did not affect the dissociation rate of the labelled lectin and since identical Scatchard plots were found using native and formaldehyde-fixed erythrocytes we conclude that there are two classes of independent Vicia graminea binding sites on human erythrocytes. Computer analysis of the Scatchard plots gave high- and low-affinity constant (7.07±1.1) · 10 7 M −1 and (0.2±0.01) · 10 7 M −1, respectively, for N erythrocytes and (1.13±0.18) · 10 7 M −1 and (0.24±0.01) · 10 7 M −1, respectively for the M cells. N erythrocytes were estimated to have 0.085 · 10 5 high-affinity and 2.1 · 10 5 low-affinity sites and M erythrocytes, 0.011 · 10 5 high affinity and 0.13 · 10 5 low-affinity sites. N cells therefore have 10-times as many sites as M cells. Studies of the dissociation of 125I-labelled lectin from N and M cells in the presence of unlabelled lectin gave dissociation rate constants of 51 · 10 −4 s −1 and 1.97 · 10 −4 s −1 for the high- and low-affinity sites of N cells and 13 · 10 −4 s −1 and 1.6 · 10 −4 s −1 for the high- and low-affinitym sites of M cells, indicating that the binding of Vicia graminea lectin to human erythrocytes is reversible.

Studies on the specificity of the binding site of Vicia graminea anti-N lectin.

Incubation of polyacrylamide gels after electrophoresis of glycoproteins with Vicia graminea lectin, labeled with radioactive iodine, showed that the lectin was bound strongly to blood‐group N and Ss human sialoglycoproteins, weakly to the major sialoglycoprotein of horse red cell membranes, and was not bound to blood‐group M sialoglycoprotein.Inhibition of binding of the labeled lectin to blood‐group NN erythrocytes by untreated and modified human and horse erythrocyte glycoproteins and their structurally defined glycopeptide fragments was studied. The glycoproteins and glycopeptides were modified by desialylation, N‐acetylation, Edman degradation or by a combination of two or more of these procedures.Desialylation and N‐acetylation incrcased thc inhibitory activity of N and M glycoproteins and glycopeptideb. The lectin was inhibited by the NH2‐terminal M and N glycopeptides of various length of the polypeptide chain, and was not inhibited by the internal tryptic glycopeptide. All modified N glycopeptides (terminated with a leucine residue) were distinctly stronger inhibitors of the lectin than respective M glycopeptides (terminated with a berine residue). In each of these two groups the most active were tryptic and pronase asialoglycopeptides with blocked amino groups. The M and N tryptic asialoglycopeptides were inactivated by Edman degradation and reactivated by the subsequent N‐acetylation.Horse erythrocyte glycoprotein and its pronase glycopeptide were relatively weak inhibitors of V. graminea lectin, their activity was increased by desialylation, but was not affected by N‐acetylation.Comparison of the structures of glycopeptides reacting and not reacting with V.graminea lectin suggested the following tentative conclusions. (a) V.graminea lectin can react with glycopeptides which have clusters of unsubdiluted or sialylated Gal(βl‐3)GalNAc‐ chains located at adjacent amino acid residues. (b) Reaction of glycopeptides with the lectin is also dependent on other (e.g. amino acid) residues present at the lectin‐binding site, namely, it is enhanced by a hydrophobic residue and is weakened by a free amino group.

Vicia graminea anti-N lectin: partial characterization of the purified lectin and its binding to erythrocytes.

Vicia graminea lectin, purified by affinity chromatography, was homogeneous in sodium dodecylsulphate/polyacrylamide gel electrophoresis and migrated with a velocity corresponding to a molecular weight of 125 000. Heating of 0.1% sodium dodecylsulphate at 100 degrees C caused dissociation of the lectin into subunits with an apparent molecular weight of 31 000. The results of isoelectric focusing suggested non-identity of the lectin subunits and existence of several molecular forms of the lectin. The lectin was neither dissociated nor activated by succinylation, but was irreversibly inactivated by 8 M urea. The lectin was totally bound to concanavalin-A-Sepharose and could be eluted with alpha-D-mannopyranoside. Binding of the 125I-labeled Vicia graminea lectin to untreated and desialylated human erythrocytes of blood groups M and N, horse and bovine erythrocytes was characterized. The lectin was bound specifically to sites specific for blood group N on untreated human erythrocytes with an uniform affinity, and association constant Ka = 1.5 X 10(8) M-1. Desialylated human NN and MM erythrocytes bound more lectin, with a distinctly higher, but non-uniform affinity. Vicia graminea lectin bound weakly to horse erythrocytes, and the effect of their desialylation was similar to that obtained with human erythrocytes. The lectin was not bound either to untreated or to desialylated bovine erythrocytes. Binding of the labeled lectin to human NN erythrocytes was inhibited by desialylated glycoproteins of the M and N blood groups, by untreated N glycoprotein, and weakly by untreated M glycoprotein.

Subunit structure of Vicia graminea anti-(blood-group N) lectin.

The subunit of the Vicia graminea lectin with blood-group-N specificity was examined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and gel filtration in 6M-guanidinium chloride, and its molecular weights was found to be 25 000. The unique N-terminal sequence fof the first nine residues of the lectin confirmed that Vicia lectin consists of four identical chains non-covalently linked. Finally the microheterogeneity of the lectin shown by analytical isoelectric focusing is discussed.

Isolation and Partial Characterization of an Epiglycanin-Like Glycoprotein From a New Non-Strain-Specific Subline of TA3 Murine Mammary Adenocarcinoma<xref ref-type="fn" rid="fn2">2</xref><xref ref-type="fn" rid="fn3">3</xref>

A new non-strain-specific ascites subline of the TA3 mammary adenocarcinoma TA3-MM, which arose in vivo from the strain-specific TA3-St subline during an acute respiratory illness of the syngeneic mouse strain A/HeHa hosts, possessed at its surface a glycoprotein not found on the parent TA3-St cell. This glycoprotein, termed TA3-MM epiglycanin, was characterized by a high molecular weight (500,000), by potent inhibition of hemagglutination by the Vicia gramines lectin, and by carbohydrate and amino acid compositions nearly identical to those of the glycoprotein epiglycanin present at the surface of the allotransplantable TA3-Ha ascites cell. By electron microscopic examination, TA3-MM epiglycanin appeared as long extended rods with widths (2.5 nm) and lengths (450--500 nm) similar to those of TA3-Ha epiglycanin. Incubation of each of two sublines of the TA3-MM ascites cell, TA3-MM/1 and TA3-MM/2, with a modified trypsin followed by column chromatography produced approximately 1.0- and 0.2-fold as much epiglycanin-like material, respectively, as was obtained from the TA3--a ascites cell. Continuous growth of the TA3-MM cell in suspension culture resulted in an almost complete disappearance of epiglycanin in a manner demonstrated earlier for the TA3-Ha cell grown under similar conditions. Allotransplantability in the TA3-MM cell may be due, at least in part, to masking a histocompatibility antigens by epiglycanin-like molecules.