Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A series of experiments were conducted to study synthesis and secretion of mucin in mucus-secreting subpopulations of HT29 human colonic adenocarcinoma cells selected by resistance to methotrexate (MTX). Mucin was quantitated by [3H]glucosamine labeling and chromatography on Sepharose CL-4B. The mucinous nature of the labeled high molecular weight glycoprotein was verified by alkaline borohydride treatment, cesium chloride density gradient ultracentrifugation, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The results of these experiments demonstrated that MTX-treated cells have increased amounts of mucin in medium, cytosol, and membrane fractions. This was associated with the increase in the activities of polypeptidyl-N-acetylgalactosaminyltransferase and beta-1,3-galactosyltransferase compared to control cells. DEAE-Sephacel chromatography of [3H]glucosamine-labeled high molecular weight glycoproteins suggest that MTX-treated cells are less acidic compared to controls. Using complementary DNA probes for two distinct human intestinal mucins (MUC2 and MUC3) and one mammary mucin (MUC1), it was found that MTX-treated cells expressed more mucin messages compared to untreated cells. These results were consistent with immunoblots using anti-MRP (MUC2 repeat peptide), anti-M3P (MUC3 repeat peptide), 139H2 (MUC1 peptide), anti-T (peanut lectin), anti-Tn (91S8), and anti-sialosyl Tn (JT10e) antibodies. These data indicate that MTX-resistant HT29 cells show enhanced secretion and synthesis of mucin as well as expression of MUC1-, MUC2-, and MUC3-related mucin polypeptide epitopes.
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PMID:Expression and characterization of mucins associated with the resistance to methotrexate of human colonic adenocarcinoma cell line HT29. 151 31

The 133-amino-acid sequences of the alpha-subunit of jacalin (a lectin from Artocarpus integrifolia) and of the slightly larger alpha'-subunit were determined. The alpha'- and alpha-subunits, in the approximate ratio of 1:3, were found to be virtually identical in their primary structures, except for one valine for isoleucine substitution at position 113. Although both alpha'- and alpha-chains were glycosylated, the extent of glycosylation in the alpha'-chain was much greater than that in the alpha-subunit. In the alpha'-polypeptide, all molecules contained an N-linked oligosaccharide at position 74 and some contained sugar at position 43. The alpha- and alpha'-subunits were found to be strongly non-covalently associated with three distinct beta-subunits containing 20 amino acids each. Electron-microscopic visualization of native jacalin disclosed a structure composed of four alpha-type subunits with a clear-cut 4-fold symmetry. Analytical-ultracentrifugation studies of jacalin revealed an average molecular mass of 65 kDa, a value compatible with a tetrameric structure of the alpha(alpha')-subunits. The recalculated number of sugar-binding sites per jacalin molecule, given a molecular mass of 65 kDa, would yield 0.8 sites per alpha(alpha')-promoter, i.e. about twice the value previously determined [Appukutan & Basu (1985) FEBS Lett. 180, 331-334; Ahmed & Chatterjee (1989) J. Biol. Chem. 264, 9365-9372].
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PMID:Structural and electron-microscopic studies of jacalin from jackfruit (Artocarpus integrifolia) show that this lectin is a 65 kDa tetramer. 152 Feb 61

A new lectin from the sponge Pellina semitubulosa is derived which was extracted and purified to homogeneity. The purified lectin is probably a hexamer of polypeptide chains (each M(r) 34,000) which are covalently linked via disulfide linkages; the isoelectric point is 6.1. The lectin displays the following specificities: D-galactose (50% inhibition of hemagglutination at 0.2 mM) = L-arabinose (0.2 mM) greater than D-fucose (1.5 mM) greater than D-glucose (3.0 mM). It precipitates human erythrocytes (A1, A2, A1B, B, and O) with a titer between 2(8) and 2(11) and erythrocytes from sheep and rabbits with a titer between 2(5) and 2(10). The Pellina lectin displays a strong mitogenic effect on spleen lymphocytes from mice. Immunochemical analyses revealed that both murine T- and B-lymphocytes display a capping of the lectin receptors on their cell surfaces after lectin treatment. Murine macrophages were found to endocytose the lectin. Pellina lectin at concentrations between 0.3 and 10.0 micrograms/ml potently enhances interleukin 1 (IL-1) release from mouse peritoneal macrophages and interleukin 2 (IL-2) production in mixed murine lymphocyte cultures.
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PMID:A novel galactose- and arabinose-specific lectin from the sponge Pellina semitubulosa: isolation, characterization and immunobiological properties. 152 Jul 31

In the hemolymph of the silkworm, Bombyx mori, lectin with hemagglutinating activity against sheep red blood cells increases at larval-larval ecdysis and at spinning stage (Suzuki and Natori, 1983) and is induced by infection with cytoplasmic polyhedrosis virus. A Bombyx lectin polypeptide with molecular weight approx 280K is responsible for hemagglutinating activity, since antiserum raised against this polypeptide inhibited hemagglutinating activity. The site of synthesis of Bombyx lectin was determined by primary tissue cultures of fat body and hemocytes. A hemagglutinating activity assay demonstrated that hemocyte is responsible for the release of hemagglutinin into the culture medium. Isolation of cDNA clones coding for Bombyx lectin was carried out on the cDNA library prepared in an expression vector lambda gt11 starting with poly(A)+ RNA from spinning larval hemocytes. As a result of immunoscreening, several positive clones were obtained, and the cDNA clones were characterized.
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PMID:Isolation of cDNA clones coding for humoral lectin of silkworm, Bombyx mori, larvae. 154 49

A procedure that combined ion exchange, gel permeation, and insulin-like growth factor-binding protein 3 (IGF-BP-3) affinity chromatography with chromatofocusing and reversed-phase high pressure liquid chromatography was used to isolate high molecular weight precursors of human insulin-like growth factor II (IGF-II) from acetic acid extracts of Cohn fraction IV1. Two precursors had isoelectric points (pI) of 5.1 and 5.4 and apparent Mr values of 15,000 and 11,500, respectively. An apparent Mr = 16,000 RLPG/Ser29 variant of IGF-II was also identified in the acetic acid extracts. Amino-terminal amino acid sequencing of the major E domain-containing peptide that had been isolated from apparent Mr = 15,000 IGF-II (pI 5.1), following its digestion with the endoprotease Lys-C, indicated the carboxyl terminus of this precursor was near or at Lys88. During the sequencing of this peptide, a sharply reduced yield of derivatized amino acid occurred at cycle 10, indicating that Thr75 had been posttranslationally modified, possibly by O-glycosylation. To evaluate this possibility, the 125I-labeled high molecular weight IGF-IIs and their endoprotease-generated peptides were treated with glycosidases, and their effects were determined from the change in relative mobilities of the polypeptide and peptides during sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Neuraminidase treatment of apparent Mr = 15,000 and 11,500 IGF-II reduced their Mr values to a common value of 10,500. When the desialylated precursors of IGF-II were treated with O-glycosidase, but not when treated with N-glycosidase, the Mr values were reduced further to about 10,000. This was the Mr value that would be predicted for an unglycosylated form of precursor IGF-II that had a carboxyl-terminal end at or near Lys88. When the Ser66-Lys88 endoprotease-generated E domain peptides from pI5.1 and 5.4 high Mr IGF-II were treated with the glycosidases, they had relative mobility changes during sodium dodecyl sulfate-polyacrylamide gel electrophoresis that were similar to those of the intact precursors. Finally, the association of O-linked oligosaccharide with the E domain peptide of IGF-II was confirmed by demonstrating the specificity of binding of the Ser66-Lys88 asialoglycopeptide to jackfruit lectin.
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PMID:The identification of O-glycosylated precursors of insulin-like growth factor II. 156 71

The relationship between cell differentiation/tumorisation and plasma membrane glycoproteins was approached using peanut agglutinin (PNA) a lectin specific for the Gal-beta(1,3)GalNAc sequence and a homologous cell system consisted of normal rat hepatocytes (HyC) and a poorly differentiated hepatoma (ZHC). This work is focused on the molecular nature of PNA receptors. PNA bound strongly to ZHC, but bound very weakly, if at all to hepatocytes. After sialidase treatment this binding was slightly enhanced in ZHC and HyC. The total number of binding sites on ZHC was 9.6 x 10(6)/cell and 1.2 x 10(7)/cell before and after sialidase treatment respectively. In contrast, this number could not be calculated on HyC, even after sialidase treatment. The PNA receptors were isolated and identified from ZHC using affinity chromatography on immobilized PNA and lectin overlay. Two bands were revealed after SDS-PAGE of PNA receptors: a major one with a relative molecular mass of 160 kDa and a minor one of 110 kDa. The latter disappeared after sialidase treatment of ZHC suggesting the possibility that these two bands could be less and more sialylated forms of the PNA receptors, respectively. In contrast no PNA receptors could be detected on HyC. These PNA receptors could be considered O-linked glycoproteins containing the Gal-beta(1,3)GalNAc disaccharide because: i) PNA carbohydrate specificity toward this disaccharide found in this glycoprotein type; ii) their carbohydrate composition with Gal and GalNAc but not man residues; iii) their sensitivity to alkaline treatment; and iv) strong inhibition of PNA binding to ZHC with the Gal-beta(1,3)GalNAc structure. The absence of PNA receptors on HyC appeared to be related to the absence of this glycoprotein containing the disaccharide but not to the change or failure of glycosylation of the polypeptide chain of PNA receptors. The relationship between the presence of PNA receptors and differentiation/tumorisation phenomena as well as the mechanism that induced the expression of these receptors are discussed.
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PMID:Identification of peanut agglutinin receptors related to the state of tumoral liver cell differentiation. 157 2

A nuclear carbohydrate-binding protein with a molecular mass of 67 kDa (CBP67), which is specific for glucose residues, was purified to essential homogeneity from rat liver nuclear extracts. This protein could also be isolated from nuclear ribonucleoprotein (RNP) complexes by extraction in the presence of 0.6 M or 2 M NaCl, but it was absent in polysomal RNP complex. The binding of the purified protein, which has an isoelectric point of 7.3, to glucose-containing glycoconjugates depends on the presence of Ca2+ and Mg2+. Using closed nuclear envelope vesicles as a system to study nuclear transport of RNA, it was shown that both entrapped polysomal mRNA and nuclear RNA precursors are readily exported from the vesicles in an ATP-dependent manner. The transport was unidirectional and strongly promoted by the poly(A) segment attached to these RNAs. In contrast, nuclear RNP complexes entrapped into the vesicles together with glucose-conjugated bovine serum albumin or nucleoplasmin, or bird nest glycoprotein, were not exported into the extravesicular space. However, transport of nuclear RNP complexes could be achieved in the presence of glucose or after co-addition of a glucose-recognizing lectin from Pellina semitubulosa. In Western blots, radioiodinated CBP67 binds to an 80-kDa polypeptide both in isolated rat liver nuclear envelopes and pore-complex laminae. From these results we postulate that CBP67 may direct nuclear RNP complexes to the nuclear pore.
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PMID:Purification of a glucose-binding protein from rat liver nuclei. Evidence for a role in targeting of nuclear mRNP to nuclear pore complex. 157 87

The asparagine-linked oligosaccharide chains of human von Willebrand factor (vWF) purified from pooled plasma were quantitatively liberated from the polypeptide moiety by hydrazinolysis. After N-acetylation, these were fractionated by paper electrophoresis and sequential chromatography on lectin-affinity columns of concanavalin A, Phaseolus vulgaris erythrophytohemagglutinin, Datura stramonium agglutinin, Ricinus communis agglutinin 120, and Ulex europaeus agglutinin I and on a Bio-Gel P-4 column. Their structures were investigated by sequential exoglycosidase digestion in conjunction with methylation analysis. The glycoprotein was shown to be unique in its great diversity of oligosaccharide structures. Another noteworthy finding which had not been reported previously was the occurrence of asparagine-linked oligosaccharide chains with blood group A, B, and H(O) structures. In the present study, this glycoprotein was shown to contain mono- (0.4% of the total oligosaccharides), bi-(78.2%), tri- (12.3%), and tetraantennary (2.3%) complex type oligosaccharides in addition to a series of high mannose type oligosaccharides, Man6-9GlcNAc2 (0.8%). Biantennary complex type oligosaccharide chains were those with (8.2%) and without (70.0%) a bisecting GlcNAc residue and approximately 13.2%, 2.2%, and 0.4% of these contained blood group H(O), A, and B structures, respectively. The tri- and tetraantennary complex type chains were those with and without N-acetyllactosamine repeats, and about 13.0% of the triantennary chains without the N-acetyllactosamine repeat contained the blood group H(O) structure. Occurrence of these asparagine-linked oligosaccharides with blood group A and B structures suggest that the repeated use of factor VIII/vWF pooled concentrate for the treatment of hemophiliacs could result in the production of antibodies against vWF with a different blood group from that of the patient, and this development may be pathogenic.
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PMID:Structures of the asparagine-linked oligosaccharide chains of human von Willebrand factor. Occurrence of blood group A, B, and H(O) structures. 157 15

The Gal/GalNAc-specific lectin on rat peritoneal macrophages (macrophage asialoglycoprotein binding protein, M-ASGP-BP) is structurally similar to rat hepatic asialoglycoprotein-binding protein (ASGP-BP) or rat hepatic lectin (RHL) and is highly homologous with the major component of RHL, RHL-1 (Ii, M, Kurata, H., Itoh, N., Yamashina, I., and Kawasaki, T. (1990) J. Biol. Chem. 265, 11295-11298). We found in this study that transfection with a cDNA clone that encodes a single polypeptide, M-ASGP-BP, was sufficient for the expression of an endocytic receptor for asialoorosomucoid (ASOR) on the COS-1 cell surface. The Kuptake value for ASOR for the transfected cells was 12.5 nM, which is similar to that for peritoneal macrophages (23 nM), and the number of ASOR bound on the cell surface was 1-8 x 10(5)/cell, this value being hundreds of times larger than that for peritoneal macrophages. 125I-ASOR bound on the surfaces of the transfected cells was rapidly internalized on incubation at 37 degrees C, and after 90 min of incubation, most of the radioactivity was recovered in acid-soluble degraded products from the medium. These results confirmed that the cDNA cloned in our previous study does in fact encode M-ASGP-BP and also that the single polypeptide chain can form a homooligomeric receptor (probably a hexamer or octamer) exhibiting high affinity for ASOR. The latter property was distinct from that of the hepatic ASGP-BP in that simultaneous transfection of two cloned cDNAs that encode RHL-1 and RHL-2/3 was required to produce an active ASOR receptor (McPhaul, M., and Berg, P. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 8863-8867). This M-ASGP-BP expression system may serve as a simple model with which to investigate the molecular mechanisms underlying carbohydrate-mediated endocytosis.
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PMID:Expression of a functional asialoglycoprotein receptor through transfection of a cloned cDNA that encodes a macrophage lectin. 157 57

Nucleotide sequence analysis of a 42-kb region of the vaccinia virus (strain Western Reserve) genome identified a gene with the potential to encode a 35.1-kDa polypeptide with properties of a membrane glycoprotein (Smith et al., J. Gen. Virol. 72, 1349-1376, 1991). The 317 amino acid open reading frame (ORF) has similarity with complement control proteins and a secretory vaccinia virus protein (C28K) which interferes with complement function. The predicted B5R gene product differs from the latter protein in that it contains a C-terminal hydrophobic sequence and may be membrane-associated rather than secretory. Transcriptional mapping by Northern blotting and S1 nuclease protection showed that the gene is transcribed both early and late during infection, with the early RNA start site located 60 bp upstream of the late start site that is present at -9 to -5 bp relative to the ORF. Nevertheless, translation of early and late mRNAs are predicted to produce the same polypeptide. A rabbit antiserum was raised to the predicted external hydrophilic domain of B5R expressed in Escherichia coli and used to immunoprecipitate a M(r) 42 K protein from vaccinia-infected cells. This protein was synthesized throughout infection, with a peak from 6 to 7 hr, and its production was inhibited by tunicamycin but not monensin. Western blotting of proteins from purified extracellular enveloped virus (EEV) or intracellular naked virus with anti-B5R serum showed that this M(r) 42 K protein and two higher molecular weight forms (Mr82 and 87 K) were present only in EEV. Anti-B5R serum inhibited comet formation by the IHD-J strain of virus on RK13 cells. B5R is the third vaccinia gene shown to encode an EEV glycoprotein, the others being the virus hemagglutinin gene, and gene SalL4R which encodes a group of lectin-like glycoproteins of M(r) 22-24 K.
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PMID:A constitutively expressed vaccinia gene encodes a 42-kDa glycoprotein related to complement control factors that forms part of the extracellular virus envelope. 158 49


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