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Biomedical subjects

R Kornfeld

Publications and source records attributed to R Kornfeld.

At least 37 records · Page 2Linked to original sources
PubMed1984

The B4 lectin from Vicia villosa seeds interacts with N-acetylgalactosamine residues on erythrocytes with blood group Cad specificity.

We have previously shown that the B4 lectin from Vicia villosa seeds interacts with N-acetylgalactosamine alpha-linked to serine or threonine in cell surface glycoproteins. In the present study, we show that the lectin also binds to Cad erythrocytes (0.44-2.78 X 10(6) sites/cell) with an association constant of 0.61-0.84 X 10(7)M-1. Variability in the number of B4 lectin binding sites in Cad erythrocytes from different individuals parallels reactivity of these erythrocytes with other N-acetylgalactosamine-binding lectins. Agglutination of Cad erythrocytes with B4 lectin is inhibited by urinary Tamm-Horsfall Sda-active glycoprotein. Since the Cad and Sda determinants share the terminal GalNAc beta 1.4----Gal sequence, our results indicate that Vicia villosa B4 lectin can also interact with terminal beta-linked N-acetylgalactosamine in closely-spaced oligosaccharide units of cell surface glycoproteins.

Acetylgalactosamine↗
PubMed1984

Biosynthesis of the adenosine deaminase-binding protein in human fibroblasts and hepatoma cells.

The adenosine deaminase-binding protein has previously been localized to the cell surface of human fibroblasts (Andy, R. J., and Kornfeld, R. (1982) J. Biol. Chem. 257, 7922-7925). In this study we examine the biosynthesis of binding protein in human fibroblasts, human hepatoma HepG2 cells, and a human kidney tumor cell line. Binding protein immunoprecipitated from radioiodinated detergent-extracted fibroblast membranes has a molecular weight of 120,000 when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. An additional band of Mr 100,000 is also present which we believe is a result of proteolysis of the 120,000 band. Purified soluble kidney binding protein has an Mr of 112,000. Binding protein from fibroblasts pulse-labeled with [35S]methionine for 15 min migrates as a 110-kDa band on sodium dodecyl sulfate-polyacrylamide gels. Within 30-60 min of chase, the intensity of the 110-kDa band is diminished, and a 120-kDa band has appeared. Binding protein reaches the cell surface of fibroblasts within 30-60 min of chase. The same results are obtained with the other cell lines studied. Thus, binding protein is initially synthesized as a precursor of 110 kDa which chases into a 120-kDa mature form. The shift of 10 kDa is probably due to processing of its oligosaccharide chains since soluble kidney-binding protein contains 7-9 complex N-linked chains. Upon endoglycosidase H treatment, the 110,000 precursor shifts to a Mr of 89,000 while the 120,000 mature band shifts to 115,000, consistent with the presence of 7-9 high mannose chains on the precursor and 1-2 high mannose chains on the mature form. These results and the presence of complex N-linked chains on binding protein were confirmed by lectin affinity chromatography of glycopeptides derived from [2-3H]mannose-labeled binding protein. Analysis of [6-3H]glucosamine-labeled binding protein indicates the presence of 1 sialic acid residue per chain.

Animals↗
PubMed1983

Evidence for an alpha-mannosidase in endoplasmic reticulum of rat liver.

An alpha-mannosidase activity has been identified in a preparation of rat liver endoplasmic reticulum and shown to be distinct from the previously described Golgi alpha-mannosidases I and II and the lysosomal alpha-mannosidase. The enzyme was solubilized with deoxycholate and separated from other alpha-mannosidases by passage over concanavalin A-Sepharose to which it does not bind. The endoplasmic reticulum alpha-mannosidase cleaves alpha-1,2-linked mannoses from high mannose oligosaccharides and, unlike Golgi alpha-mannosidase I, is active against p-nitrophenyl-alpha-D-mannoside (Km = 0.17 mM). It has no activity toward GlcNAc-Man5GlcNAc2 peptide, the specific substrate of the Golgi alpha-mannosidase II. The endoplasmic reticulum alpha-mannosidase activity toward p-nitrophenyl-alpha-D-mannoside is relatively insensitive to swainsonine, an inhibitor of both the lysosomal alpha-mannosidase and Golgi alpha-mannosidase II. We propose that the endoplasmic reticulum alpha-mannosidase is responsible for the removal of mannose residues from asparagine-linked high mannose type oligosaccharides prior to their entry into the Golgi.

Animals↗
PubMed1983

The B4 lectin from Vicia villosa seeds interacts with N-acetylgalactosamine residues alpha-linked to serine or threonine residues in cell surface glycoproteins.

We have examined the carbohydrate binding specificity of the B4 lectin from Vicia villosa seeds. The B4 lectin agglutinates Tn-exposed erythrocytes specifically and binds to these erythrocytes (1.4 X 10(6) sites/cell) with an association constant of 4.2 X 10(7) M-1. The concentrations of saccharides and glycopeptides of defined structure which cause 50% inhibition of B4 lectin binding to Tn-exposed erythrocytes were determined. N-Acetylgalactosamine is the best monosaccharide inhibitor, causing 50% inhibition of binding at a concentration of 0.04 mM. Other monosaccharides inhibit lectin binding in the following order of decreasing potency: N-acetylgalactosamine greater than methyl-alpha-galactopyranoside greater than p-nitrophenyl-alpha- or beta-galactopyranoside greater than methyl-beta-galactopyranoside, galactose greater than galactosamine greater than mannose, N-acetylglucosamine. The disaccharide Gal beta 1,3GalNAc causes 50% inhibition of binding at a concentration of 2.8 mM, a concentration similar to that of the p-nitrophenyl-alpha- or beta-galactopyranosides. Glycopeptides containing O-glycosidically linked oligosaccharide units are significantly more potent inhibitors of lectin binding than the oligosaccharide units alone. The most potent glycopeptide inhibitor is a fetuin glycopeptide containing two alpha-linked N-acetylgalactosamine units. This glycopeptide causes 50% inhibition of lectin binding at a concentration of 0.00034 mM and probably closely resembles the B4 lectin binding site on Tn-exposed erythrocytes.

Acetylgalactosamine↗
PubMed1983

Isolation and characterization of lectins from Vicia villosa. Two distinct carbohydrate binding activities are present in seed extracts.

An uncharacterized lectin from Vicia villosa seeds has been reported to bind specifically to mouse cytotoxic T lymphocytes (Kimura, A., Wigzell, H., Holmquist, G., Ersson, B., and Carlsson, P., (1979) J. Exp. Med. 149, 473-484). We have found that V. villosa seeds contain at least three lectins which we have purified by affinity chromatography on a column of immobilized porcine blood group substances eluted with varying concentrations of N-acetylgalactosamine and by anion exchange chromatography. The three lectins are composed of two different subunits with Mr = 35,900 (subunit B) and 33,600 (subunit A), estimated from their mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Sedimentation equilibrium analysis suggests that the purified lectins are tetramers. They have been designated B4, A4, and A2B2 to indicate their apparent subunit compositions. The purified B4 and A4 lectins contain 6.7-9.8% carbohydrate by weight; in addition, both are rich in the acidic and hydroxylic amino acids and lack cysteine and methionine. The A4 lectin agglutinates A erythrocytes specifically and binds to A1 erythrocytes (273,000 sites/cell) with an association constant of 1.8 X 10(7) M-1. Although a blood group A agglutinating activity was recognized in the original preparation of V. villosa lectins, lectins with this activity were obtained in relatively small amounts from seed extracts. The predominant lectin in V. villosa seeds, B4, does not agglutinate A, B, or O erythrocytes.

Amino Acids↗
PubMed1982

The adenosine deaminase binding protein of human skin fibroblasts is located on the cell surface.

We have studied the cellular localization of human adenosine deaminase binding protein in human skin fibroblasts. The binding activity sediments with the membrane fractions in a subcellular fractionation, and anti-binding protein antiserum reacts with the cell surface of intact fibroblasts, as shown by indirect immunofluorescence. The surface of intact fibroblasts binds 125I-labeled adenosine deaminase with an apparent KD of 0.26 units/ml and a maximum binding capacity of 553 milliunits/mg of cell protein. This binding is inhibited by antibinding protein antiserum. We conclude that most, if not all, of the adenosine deaminase binding protein is located on the cell surface.

Carrier Proteins↗
PubMed1981

The carbohydrate-binding specificity of pea and lentil lectins. Fucose is an important determinant.

The carbohydrate-binding specificities of pea lectin and lentil lectin have been determined by testing the ability of radioactively labeled glycopeptides to bind to columns of pea lectin-Sepharose and lentil lectin-Sepharose. The presence of a fucose residue attached to the asparagine-linked N-acetylglucosamine residue of the test glycopeptide was essential for high affinity binding to both pea and lentil lectin-Sepharose but not to concanavalin A-Sepharose. In addition to fucose, 2 alpha-mannosyl residues were required for glycopeptide binding to the pea and lentil lectin-Sepharose columns. Substitution of the alpha-mannosyl residues at C-2 did not prevent their interaction. Substitution of 1 alpha-mannosyl residue at both C-2 and C-4 did prevent glycopeptide binding, but substitution of 1 alpha-mannosyl residue at C-2 and C-6 did not impair binding. Glycopeptide binding to lentil lectin-Sepharose was enhanced by the exposure of terminal N-acetylglucosamine residues on the glycopeptide, whereas binding to pea lectin-Sepharose was enhanced by the exposure of terminal mannose residues. The differences in carbohydrate binding specificity of pea lectin-Sepharose and Con A-Sepharose were exploited to fractionate a mixture of [2-3H]mannose-labeled glycopeptides derived from mouse lymphoma cell glycoproteins.

Carbohydrate Conformation↗
PubMed1981

Structures of the oligosaccharides of the glycoprotein coded by early region E3 of adenovirus 2.

Early region E3 of adenovirus 2 encodes a glycoprotein, E3-gp25K, that is a good model with which to study structure-function relationships in transmembrane glycoproteins. We have determined the structures of the oligosaccharides linked to E3-gp25K. The oligosaccharides were labeled with [2-(3)H]mannose in adenovirus 2-early infected KB cells for 5.5h (pulse) or for 5.5 h followed by a 3-h chase (pulse-chase). E3-gp25K was extracted and purified by chromatography on DEAE-Sephacel in 7 M urea, followed by gel filtration on a column of Bio-Gel A-1.5m in 6 M guanidine hydrochloride. An analysis of the purified protein by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that it was >95% pure. The oligosaccharides were isolated by pronase digestion followed by gel filtration on a column of Bio-Gel P-6, then by digestion with endo-beta-N-acetylglucosaminidase H, followed by gel filtration on Bio-Gel P-6, and finally by paper chromatography. The pulse sample contained equal amounts of Man(9)GlcNAc and Man(8)GlcNAc and small amounts of Man(7)GlcNAc and Man(6)GlcNAc. The pulse-chase sample had predominantly Man(8)GlcNAc and much less Man(9)GlcNAc, indicating that processing of the Man(9)GlcNAc to Man(8)GlcNAc had occurred during the chase period. Thus, Man(8)GlcNAc is the major oligosaccharide on mature E3-gp25K. The structures of these oligosaccharides were established by digestion with alpha-mannosidase, methylation analysis, and acetolysis. The oligosaccharides found had typical high-mannose structures that have been observed in other membrane and soluble glycoproteins, and the branching patterns and linkages of the mannose residues of Man(9)GlcNAc were identical to those of the lipid-linked Glc(3)Man(9)GlcNAc(2) donor. Thus, adenovirus 2 infection (early stages) apparently does not affect the usual cellular high-mannose glycosylation pathways, and despite being virus coded, E3-gp25K is glycosylated in the same manner as a typical mammalian cell-coded glycoprotein.

Adenoviruses, Human↗
PubMed1979

Structure of the high mannose oligosaccharides of a human IgM myeloma protein. I. The major oligosaccharides of the two high mannose glycopeptides.

The structures of the predominant high mannose oligosaccharides present in a human IgM myeloma protein (Patient Wa) have been determined. The IgM glycopeptides, produced by pronase digestion, were fractionated on DEAE-cellulonalysis shows that glycopeptide I contains Asn, Pro, Ala, Thr, and His and glycopeptide II contains Asn, Val, and Ser, which are the same amino acids found in the sequences around Asn 402 and Asn 563 respectively, to which high mannose oligosaccharides are attached in IgM (Patient Ou) (Putnman, F.W., Florent, G., Paul, C., Shinoda, T., and Shimizu, A. (1973) Science 182, 287-290). The high mannose glycopeptides in IgM (Wa) exhibit heterogeneity in the oligosaccharide portion. Structural analysis of the major oligosaccharides indicates that the simplest structure is: (see article of journal). The larger oligosaccharides present have additional mannose residues linked alpha 1 yields 2 to terminal mannose residues in the above structure. Glycopeptide I contains primarily Man5 and Man6 species, while glycopeptide II contains Man6 and Man8 species. The two Man6 oligosaccharides have different branching patterns.

Amino Acids↗
PubMed1979

Structure of the high mannose oligosaccharides of a human IgM myeloma protein. II. The minor oligosaccharides of high mannose glycopeptide.

The high mannose glycopeptide I from IgM (Patient Wa) contains, in addition to the two major oligosaccharides described earlier (Chapman, A., and Kornfeld, R. (1979) J. Biol Chem. 254, 816-823), four minor oligosaccharides. After release from glycopeptide I by endo-beta-N-acetylglucosaminidase Cu and reduction with NaBH4, all four oligosaccharides have been shown to have the basic structure: (see article of journal). Oligosaccharide IA-1 (Man9GlcitolNAc) has additional alpha1,2-linked mannose residues attached to positions a and b, and the sequence Man alpha1,2 yields to Man alpha1,2 yields to attached at position c. Oligosaccharide IA-2 (Man8GlcitolNAc) has additional alpha1,2-linked mannose residues attached to positions a, b, and c. Oligosaccharide IA-3 (Man7GlcitolNAc) has additional alpha1,2-linked mannose residues at positions b and c. In contrast, oligosaccharide IA-4 has a single N-acetyglucosamine residue beta1,2-linked to the mannose at position c. Oligosaccharides IA-1, -2 and -3 are thought to represent "processing" intermediates that are precursors of the major Man6 and Man5 oligosaccharides of glycopeptide I. IA-4 may arise from the Man5 oligosaccharide by the action of UDP-GlcNAc:glycoprotein N-acetylglucosaminyl-transferase, which catalyzes the first reaction leading to complex oligosaccharide synthesis.

Carbohydrates↗
PubMed1978

Structure of the oligosaccharides of three glycopeptides from calf thymocyte plasma membranes.

The carbohydrate composition and oligosaccharide structure of three glycopeptides isolated from delipidated calf thymocyte plasma membranes following Pronase digestion have been determined. Five major glycopeptide fractions were separated using Bio-Gel P-6 gel filtration and diethylaminoethylcellulose chromatography. The structure of the oligosaccharide chains of three of these glycopeptides was determined by a combination of sequential degradation with glycosidases and methylation analysis. These oligosaccharide structures consist of complex, highly branched N-linked chains containing at their nonreducing termini the unusual sequence Gal(beta1 leads to 3)Gal(beta1 leads to 4)GlcNAc leads to as well as the more usual sequence SA(alpha2 leads to 3)Gal(beta1 leads to 4)GlcNAc leads to. In addition, one glycopeptide also contains short O-linked chains with the structure Gal(beta leads to 3)GalNAc leads to Ser(Thr) which have receptor activity for the lectin from the mushroom Agaricus bisporus.

Agaricales↗
PubMed1976

Comparative aspects of glycoprotein structure.

Glycoproteins have a wide distribution in nature and serve a vast number of functions. There are glycoprotein enzymes and hormones; glycoproteins are found in blood and secretions, in cell membranes, and in connective tissue. Of all the biologically occurring macromolecules the glycoproteins, which consist of carbohydrate moieties convalently linked to a polypeptide backbone, represent the most diverse group, ranging from substances in which the carbohydrate component represents less than 1% of the total weight to those in which it represents over 80% of the total. The proteoglycans, which are classified separately from other glycoproteins and include the chondroitin sulfates, dermatan sulfates, and heparin primarily carbohydrate in the form of numerous heteropolysaccharide chains attached to a polypeptide chain at closely spaced intervals. The sugars that commonly occur in glycoproteins include galactose, mannose, glucose. N-acetylglucosamine, N-acetylgalactosamine, sialic acids, fucose, and xylose. The proteoglycans also contain various uronic and sulfated amino sugars.

Animals↗
PubMed1975

Interaction of immunoglobulin glycopeptides with concanavalin A.

A number of intact and partially degraded immunoglobulin glycopeptides have been tested for their ability to interact with concanavalin A. The degraded glycopeptides were prepared by using purified glycosidases to remove sugar residues from the nonreducing ends of the oligosaccharide chains of intact glycopeptides. A quantitative and sensitive assay was devised to measure the potency of the glycopeptides as haptene inhibitors of 125I-concanavalin A binding to guinea pig erythrocytes. The most potent haptene, derived from an immunoglobulin G glycopeptide, had a branched chain oligosaccharide with two GlcNAc (see article) Man (see article) nonreducing termini linked to a mannose residue in the core. The other very potent glycopeptide was an immunoglobulin E high mannose glycopeptide which contained 3 terminal alpha-mannose residues and 1 internal 2-O-mannose residue. Removal of terminal beta-N-acetylglucosamine residues or alpha-mannose residues reduced the activity of these and other glycopeptides as inhibitors of 125I-concanavalin A binding. It was concluded that the ability of these glycopeptides to interact with concanavalin A is dependent on their content of terminal beta-N-acetylglucosamine residues, terminal alpha-mannose residues, and also internal mannose residues substituted on the C-2 hydroxyl group, and that the saccharide combining site of concanavalin A must be able to bind several sugar residues.

Animals↗