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)

The heparan sulfate proteoglycan of the bovine glomerular basement membrane (Mr = 200,000, 30% carbohydrate by weight) has been deglycosylated by various chemical and enzymatic procedures to identify the core protein and provide information about the N- and O-linked saccharide units. Heparitinase digestion of the proteoglycan reduced its Mr to 143,000, consistent with the removal of its four glycosaminoglycan chains with the exception of short segments adjacent to the carbohydrate-protein linkage region, whereas nitrous acid treatment brought about a smaller reduction in size (to Mr = 168,000) which was shown to be due to the resistance of the internal portion of the heparan sulfate polymer to this reagent. Incubation of the heparitinase-digested proteoglycan with peptide N-glycosidase F decreased its Mr by about 8,000 and liberated oligosaccharides which were primarily acidic in nature; since endo-beta-N-acetylglucosaminidase H did not bring about any saccharide release, it appears that the N-linked carbohydrate units (three per molecule) occur exclusively as the complex type. Treatment of the proteoglycan with trifluoromethanesulfonic acid, a reagent which cleaves all saccharide units, yielded the core protein which migrated as a single discrete band (Mr = 128,000) on polyacrylamide gel electrophoresis. Although the native and heparitinase-treated proteoglycan reacted with concanavalin A and Bandeiraea simplicifolia I, the core protein had no affinity for these lectins, and this loss of reactivity can be attributed to the removal of the N- and small O-linked saccharides. However, the immunoreactivity of the deglycosylated protein with antiserum directed against the intact proteoglycan was to a large measure (80%) preserved, suggesting that the polyclonal response to this glomerular basement membrane glycoconjugate is primarily directed against determinants on the polypeptide portion.
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PMID:Selective deglycosylation of the heparan sulfate proteoglycan of bovine glomerular basement membrane and identification of the core protein. 295 58

Using the lambda gt11 expression library of murine teratocarcinoma cells, we isolated cDNA clones encoding a core protein carrying a developmentally regulated carbohydrate marker, namely the binding site for Dolichos biflorus agglutinin. The deduced amino acid sequence of the polypeptide (molecular weight, 37,102) revealed a leader sequence, nine potential asparagine glycosylation sites, and a transmembrane region. Sequence homology to variable domain of immunoglobulin kappa chain has been detected in a domain; homologous amino acids near cysteine residues are those conserved in many members of the immunoglobulin gene superfamily. In contrast to other members of the superfamily, the core protein gene was significantly expressed in embryonal carcinoma cells, which are similar to undifferentiated cells of early embryos.
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PMID:A teratocarcinoma glycoprotein carrying a developmentally regulated carbohydrate marker is a member of the immunoglobulin gene superfamily. 296 22

Cultured mouse mammary (NMuMG) cells produce heparan sulfate-rich proteoglycans that are found at the cell surface, in the culture medium, and beneath the monolayer. The cell surface proteoglycan consists of a lipophilic membrane-associated domain and an extracellular domain, or ectodomain, that contains both heparan and chondroitin sulfate chains. During culture, the cells release into the medium a soluble proteoglycan that is indistinguishable from the ectodomain released from the cells by trypsin treatment. This medium ectodomain was isolated, purified, and used as an antigen to prepare an affinity-purified serum antibody from rabbits. The antibody recognizes polypeptide determinants on the core protein of the ectodomain of the cell surface proteoglycan. The reactivity of this antibody was compared with that of a serum antibody (BM-1) directed against the low density basement membrane proteoglycan of the Englebarth-Holm-Swarm tumor (Hassell, J. R., W. C. Leyshon, S. R. Ledbetter, B. Tyree, S. Suzuki, M. Kato, K. Kimata, and H. Kleinman. 1985. J. Biol. Chem. 250:8098-8105). The BM-1 antibody recognized a large, low density heparan sulfate-rich proteoglycan in the cells and in the basal extracellular materials beneath the monolayer where it accumulated in patchy deposits. The affinity-purified anti-ectodomain antibody recognized the cell surface proteoglycan on the cells, where it is seen on apical cell surfaces in subconfluent cultures and in fine filamentous arrays at the basal cell surface in confluent cultures, but detected no proteoglycan in the basal extracellular materials beneath the monolayer. The amino acid composition of the purified medium ectodomain was substantially different from that reported for the basement membrane proteoglycan. Thus, NMuMG cells produce at least two heparan sulfate-rich proteoglycans that contain distinct core proteins, a cell surface proteoglycan, and a basement membrane proteoglycan. In newborn mouse skin, these proteoglycans localize to distinct sites; the basement membrane proteoglycan is seen solely at the dermal-epidermal boundary and the cell surface proteoglycan is seen solely at the surfaces of keratinocytes in the basal, spinous, and granular cell layers. These results suggest that although heparan sulfate-rich proteoglycans may have similar glycosaminoglycan chains, they are sorted by the epithelial cells to different sites on the basis of differences in their core proteins.
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PMID:Mouse mammary epithelial cells produce basement membrane and cell surface heparan sulfate proteoglycans containing distinct core proteins. 296 52

Three groups of monoclonal antibodies which reacted with cells infected by guinea-pig cytomegalovirus (GPCMV) were prepared. The first group of antibodies immunoprecipitated a 50 000 mol. wt. (50K) polypeptide of GPCMV-infected cells. This polypeptide was identified as part of the nuclear inclusion by immunofluorescence. This nuclear fluorescence was markedly diminished when the infected cells were incubated in the presence of phosphonoacetic acid. By immunoelectron microscopy the antibodies reacted mainly with filamentous structures (26 to 28 nm in diameter) in nuclear inclusions and occasionally stained nucleocapsids. Neither intracytoplasmic nor extracellular virions reacted with the antibodies. Therefore, the 50K protein with which the monoclonal antibodies reacted was nuclear inclusion-specific and a non-structural protein. The second group of antibodies reacted with a 76K polypeptide of the infected cells which was a matrix protein found in both cytoplasmic inclusions and extracellular dense virions. The third group of antibodies mainly reacted with a virion core protein by immunoelectron microscopy.
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PMID:Monoclonal antibodies to guinea-pig cytomegalovirus: an immunoelectron microscopic study. 300 31

Exposure of antimycin-treated Complex III (ubiquinol-cytochrome c reductase) purified from bovine heart mitochondria to [3H]succinic anhydride plus [35S]p-diazobenzenesulfonate (DABS) resulted in somewhat uniform relative labeling of the eight measured subunits of the complex by [3H]succinic anhydride. In contrast, relative labeling by [35S]DABS was similar to [3H]succinic anhydride for the subunits of high molecular mass, i.e., core proteins, cytochromes, and the iron-sulfur protein, but greatly reduced for the polypeptides of molecular mass below 15 kDa. With Complex II depleted in the iron-sulfur protein the relative labeling of core protein I by exposure of the complex to [3H]succinic anhydride was significantly enhanced, whereas labeling of the polypeptides represented by SDS-PAGE bands 7 and 8 was significantly inhibited. Dual labeling of the subunits of Complex III by 14C- and 3H-labeled succinic anhydride before and after dissociation of the complex by sodium dodecyl sulfate, respectively, was measured with the complex in its oxidized, reduced, and antimycin-inhibited states. Subunits observed to be most accessible or reactive to succinic anhydride were core protein II, the iron-sulfur protein, and polypeptides of SDS-PAGE bands 7,8, and 9. Two additional polypeptides of molecular masses 23 and 12kDa, not normally resolved by gel-electrophoresis, were detected. Reduction of the complex resulted in a significant change of 14C/3H labeling ratio of core protein only, whereas treatment of the complex with antimycin resulted in decreases in 14C/3H labeling ratios of core proteins I and II, cytochrome c1, and a polypeptide of molecular mass 13kDa identified as an antimycin-binding protein.
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PMID:Differential labeling of the subunits of respiratory complex III with [3H]succinic anhydride, [14C]succinic anhydride, and p-diazobenzene-[35S]sulfonate. 300 48

The effect of the histidine-modifier ethoxyformic anhydride (EFA) on the enzymatic properties of the mitochondrial b-c1 complex (ubiquinol-cytochrome c reductase) has been investigated. Chemical modification by EFA inhibited to the same extent the reductase and the proton translocating activity of the complex. In particular EFA modification of the complex resulted in: strong inhibition of the antimycin-insensitive reduction of b cytochromes; inhibition of the antimycin-promoted oxidant-induced reduction of b cytochromes and inhibition of oxidation of pre-reduced b cytochromes. Analysis of the absorbance at 238 nm, indicative of N-(ethoxyformyl)histidine derivative, of the various polypeptide subunits separated by high-pressure liquid chromatography procedure, showed that EFA modified residues in core proteins and in the low-molecular-mass proteins. Both the inhibition of the redox and the protonmotive activity of the complex and the absorbance increase at 238 nm of the core protein fraction were readily reversed by hydroxylamine, indicating that modification of histidine residue(s) in core protein(s) is critical for the activity of the complex. This was supported by the finding that modification of the reductase with EFA prevented binding of fluorescein isothiocyanate to histidine residue(s) in core protein II. EFA modification of the reductase was without effect on the binding of N-(7-dimethylamino-4-methylcoumarinyl)maleimide to the various polypeptides of the complex except for the binding to the Fe-S protein which was greatly potentiated. Thus primary chemical modification of histidine residue(s) in core protein (II) appears to cause, in turn, a conformational change in the Rieske Fe-S protein.
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PMID:Chemical modification studies of beef-heart mitochondrial b-c1 complex. Effect of modification by ethoxyformic anhydride. 302 88

Chondrocytes isolated from the Swarm rat chondrosarcoma were incubated in culture with [1-3H]glucose for 30 min to 8 h. Labeled proteoglycans were isolated, treated with borohydride under alkaline conditions, and the three complex sugar structures purified: N- and O-linked oligosaccharides and chondroitin sulfate chains. The amount of incorporated radioactivity into each component sugar was analyzed by HPLC after enzyme digestion and hydrolysis. The kinetic data for labeling of each sugar over the time course of the experiment were fit to first-order rate equations and the half times (t1/2) to linear labeling were calculated. The t1/2 values were essentially the same, 5-8 min, for galactose in all three complex sugar structures and for chain glucuronic acid in chondroitin sulfate, while that for xylitol in chondroitin sulfate, 15.8 min, was significantly longer. Thus, oligosaccharide synthesis is concomitant with chondroitin sulfate chain synthesis; the addition of the chondroitin sulfate linkage galactose occurs at or nearly at the same time as chain elongation while the addition of linkage xylose residues to the core protein may precede chain synthesis by up to 8 min. Since the intracellular t1/2 of the core protein precursor for these cells is 45 to 90 min, the data strongly suggest that the addition of xylose is not completed to any significant extent while the polypeptide is still nascent or shortly after its release into the rough endoplasmic reticulum. It is proposed that the addition of xylose to the core protein precursor is a late endoplasmic reticulum or early Golgi event. The analytical data were consistent with the presence of ester phosphate on about 80% of the xylose residues of the newly synthesized proteoglycan.
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PMID:Post-translational events in proteoglycan synthesis: kinetics of synthesis of chondroitin sulfate and oligosaccharides on the core protein. 309 52

Twelve homosexual males who seroconverted to human immunodeficiency virus (HIV) were followed-up for over two years. Analysis of sera by immunoblotting showed that seroconversion was characterized by the presence of specific IgM that reacted mainly with viral polypeptides of molecular weights ranging from 17 Kd to 55 Kd. Specific IgG to all HIV proteins was detected. Immunoblotting showed that antibodies to 24 Kd core protein alone or in association with 17 Kd polypeptide appeared first in some cases. Virus antigen was detected in six patients: five subjects were positive at the time of seroconversion, and one became positive afterwards. It is concluded that detection of IgG and IgM antibody against the different viral polypeptides, together with detection of viral antigen is necessary in order to determine the stage of HIV infection.
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PMID:Serological study of subjects with seroconversion to human immunodeficiency virus. 313 1

Transforming growth factor beta (TGF-beta) is a polypeptide growth factor that affects the accumulation of extracellular matrix by many cell types. We have examined the ability of mouse mammary epithelial (NMuMG) cells to respond to TGF-beta and assessed the effect of the growth factor on the expression of their cell surface heparan sulfate/chondroitin sulfate hybrid proteoglycan. NMuMG cells respond maximally to 3 ng/ml TGF-beta and the response is consistent with occupancy of the type III receptor. However, cells that are polarized, as shown by sequestration of the cell surface PG at their basolateral surfaces, must have the growth factor supplied to that site for maximal response. Immunological quantification of proteoglycan core protein on treated cells suggests that the cells have an unchanging number of this proteoglycan at their cell surface. Nonetheless, metabolic labeling with radiosulfate shows a approximately 2.5-fold increase in 35SO4-glycosaminoglycans in this proteoglycan fraction, defined either by its lipophilic, antigenic, or cell surface properties. Kinetic studies indicate that the enhanced radiolabeling is due to augmented synthesis, rather than slower degradation. Analysis of the glycosaminoglycan composition of the proteoglycan shows an increased amount of chondroitin sulfate, suggesting that the increased labeling per cell may be attributed to an augmented synthesis of chondroitin sulfate glycosaminoglycan on the core protein that also bears heparan sulfate, thus altering the proportions of these two glycosaminoglycans on this hybrid proteoglycan. We conclude that TGF-beta may affect NMuMG cell behavior by altering the structure and thus the activity of this proteoglycan.
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PMID:Altered structure of the hybrid cell surface proteoglycan of mammary epithelial cells in response to transforming growth factor-beta. 314 30

Human embryonal carcinoma cells sometimes display the developmental potential of early embryonic stem cells. While available data do not clearly identify a counterpart of these tumor cells in normal development, previous comparisons of human embryonal carcinoma and yolk sac carcinomas indicated that these cell types are closely related, and suggested that embryonal carcinoma cells might resemble the progenitors of extraembryonic endoderm. To analyse further cell-differentiation lineage in these tumors, we produced monoclonal antibodies to cytostructurally associated antigens of human embryonal carcinoma cells. Spleen cells from mice immunized with a detergent-insoluble extract of cultured human embryonal carcinoma cells were fused to NS-1 myeloma cells, and hybridoma supernatants were screened by indirect immunofluorescence on the immunizing cell line, then on a panel of cell lines derived from human embryonal carcinomas, yolk sac carcinomas, and a range of neoplastic and normal tissues. Monoclonal antibody GCTM-1 stained the nuclei of all human cells tested and served as a positive control; this antibody immunoprecipitated proteins of 85 and 66 k Da from human embryonal carcinoma cells. GCTM-2 recognized an epitope on a 200-k Da extracellular protein present on the surface of embryonal carcinoma cells, and stained the surface of visceral yolk sac-type carcinoma and colorectal carcinoma cells as well. Enzymatic analysis of carbohydrate residues on the GCTM-2 antigen revealed that it was a keratan sulphate proteoglycan, and suggested that the epitope recognized by the antibody lies on the core protein. In immunoblots, antibody GCTM-3 bound to a 57-k Da cytoskeletal protein expressed in human embryonal carcinoma. This antibody decorated filamentous arrays in cell lines from human embryonal carcinoma, visceral yolk sac carcinoma, parietal yolk sac carcinoma (endodermal sinus tumour), and adenocarcinoma and large cell carcinoma of the lung. Antibody GCTM-4 recognized a determinant present on a 69-k Da polypeptide, associated with a component of the lysosomal compartment, which was expressed in embryonal carcinoma cells, but no other cell type tested. The results with this antibody panel thus allow distinction between human embryonal carcinoma and yolk sac carcinoma, but provide further evidence of a close relationship between these cell types.
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PMID:Analysis of cell-differentiation lineage in human teratomas using new monoclonal antibodies to cytostructural antigens of embryonal carcinoma cells. 324 84


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