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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The interaction between the plant lectin concanavalin A (Con A) and hepatic receptors for human growth hormone (GH) has been studied in particulate and soluble microsomal membrane preparations from rabbit and rat liver. Con A shows a dose-dependent, partial (30%) inhibition of 125I-human GH binding which is reversed by the Con A competitor, alpha-methyl mannoside. The Con A effect is dependent on the receptor concentration. The inhibition by Con A in rabbit liver is a reflection of a decreased number of available binding sites--there is no effect on binding affinity. It would appear that Con A binds directly to the GH-binding protein and not to an adjacent membrane glycoprotein. The GH receptor may consist of more than one molecular species, differing only in the carbohydrate type or content.
Mol Cell Endocrinol 1979 Nov
PMID:Interaction between the hepatic growth hormone receptor and concanavalin A. 22 48

This review summarizes some recent studies on the surface glycoproteins of human thymocytes and T lymphocytes. Purified cells were surface labeled by the galactose oxidase-NaB3H4 or periodate-NaB3H4 techniques. The radioactive membrane glycoproteins were separated by polyacrylamide slab gel electrophoresis and visualized by fluorography. Thymocytes and T lymphocytes show characteristic surface glycoprotein profiles which are easily distinguishable from those of the other main groups of human leukocytes. We observed specific changes in the surface glycoprotein patterns which correlate with the degree of maturation and functional activation of T cells. Surface molecules carrying T cell specific antigens were identified by immune-precipitation from lysates of surface labeled thymocytes and T lymphocytes using rabbit anti-human T cell antibodies. Finally we describe a leukocyte membrane glycoprotein which is a precursor of serum alpha 1 acid glycoprotein (orosomucoid).
Mol Cell Biochem 1979 Oct 15
PMID:Surface glycoproteins of resting and activated human T lymphocytes. 31 14

Signal transduction in eukaryotic cells is a complex process mediated, normally, by the interaction of soluble extrinsic protein factors and their cognate receptors. One example of this phenomena is the inflammatory cytokine interleukin-6 and the IL-6 receptor. However, the IL-6 receptor, once its ligand is bound, associates with another membrane glycoprotein, gp130, to potentiate the cytokine response. To further understand the basis of this interaction, and its possible implications in cellular transforming events, the corresponding gene(s) must be studied. Here we find that the human gp130 gene product is homologous to two distinct chromosomal loci on chromosomes 5 and 17. Furthermore, the presence of two distinct gp130 gene sequences is restricted to primates and is not found in other vertebrates.
Somat Cell Mol Genet 1992 Sep
PMID:Chromosomal localization of the IL-6 receptor signal transducing subunit, gp130 (IL6ST). 147 13

Immunization with the GP46/M-2 membrane glycoprotein of Leishmania amazonensis has been shown to induce a protective immune response against infection. We have surveyed a variety of trypanosomatid species and genera for the presence and expression of this gene family, information that will be relevant to future vaccine studies against leishmaniasis. Molecular karyotype analysis revealed the presence of GP46/M-2 genes in all members of the Leishmania mexicana complex, Leishmania major, Leishmania donovani, Leishmania tarentolae, and Crithidia fasciculata. In contrast, DNAs from species of the Leishmania braziliensis complex (L. braziliensis, Leishmania guyanensis, and Leishmania panamensis) failed to hybridize to GP46/M-2 probes. Western blot analyses with several polyclonal antisera against the GP46/M-2 protein revealed protein expression in L. major and L. donovani, but not L. panamensis or L. braziliensis. Phylogenetic analysis suggests that a loss of the GP46A gene family occurred following separation of the L. braziliensis complex, prior to speciation events within this complex. These data indicate that GP46/M-2 membrane glycoprotein may not be critical to parasite survival, but may play an ancillary role during the developmental cycle.
Mol Biochem Parasitol 1992 Jan
PMID:Loss of the GP46/M-2 surface membrane glycoprotein gene family in the Leishmania braziliensis complex. 154 9

The differentiated phenotype of the alveolar type II cell is rapidly altered in vitro. To evaluate factors that might influence this process, we isolated and plated rat type II cells in serum-supplemented media to promote adherence and then maintained the cells in a simple nutrient medium in the absence (S- cells) or presence (S+ cells) of serum for 5 to 7 d. The type II S- cells remained metabolically active. Despite protein synthesis that was 50% that of S+ cells, S- cells continued to synthesize a broad spectrum of proteins and to express several features of type II cell differentiation. They synthesized an apical integral membrane glycoprotein, Maclura pomifera agglutinin (MPA)-gp200, and a cytokeratin, No. 19, while S+ cells did not. When supplemented with linoleic acid, S- cells contained lamellar and multivesicular bodies, incorporated cell surface MPA into these structures, and secreted their phosphatidylcholine (PC) in response to mastoparan. Despite the relative synthesis of higher levels of total and saturated PC in S- cells supplemented with linoleic acid, phosphatidylglycerol remained diminished. A surfactant protein (SP-A) was present in S- cells, but synthesis was not detected. These studies demonstrate that serum accelerates the loss of type II cell differentiation in vitro and that the expression of type II cell markers of differentiation is not inherently linked.
Am J Respir Cell Mol Biol 1990 Oct
PMID:Serum accelerates the loss of type II cell differentiation in vitro. 169

Biochemical features of the immunologically protective, membrane glycoprotein GP46/M-2 of Leishmania amazonensis have been investigated. The protein appears to have a single carbohydrate side chain of approximately 3 kDa, representing 7% of the mass of the mature GP46/M-2 protein. Experiments removing this carbohydrate side chain from GP46/M-2 indicate that the carbohydrate is not involved in the epitope recognized by the monoclonal antibody, M-2. As this monoclonal antibody recognizes a species-specific epitope, these data suggest that this determinant is defined by the polypeptide portion of the molecule. Studies employing the VSG-lipase as well as anti-CRD antibody clearly indicate that the molecule is anchored to the surface membrane of the promastigote via a phosphatidylinositol-linked lipid anchor. Neither the carbohydrate side chain nor the lipid anchor appear to be responsible for the apparent refractoriness of this protein to protease digestion, suggesting that properties of the polypeptide itself may be responsible. These data are discussed in terms of recent DNA-derived protein sequence of the GP46/M-2.
Mol Biochem Parasitol 1991 Aug
PMID:Biochemical characterization of the protective membrane glycoprotein GP46/M-2 of Leishmania amazonensis. 171 17

A family of Schistosoma mansoni proteins (18-22 kDa, pI 5.3-5.8) are biosynthesized in juvenile worms and immunoprecipitated by antibodies uniquely present in protective Fischer rat antiserum. A cDNA clone, lambda gt11-40, expressing epitopes common to this protein family was used to obtain a genomic DNA clone, by hybridization with a lambda gt11-40 oligonucleotide probe. In the 1.37 kb of genomic DNA sequenced, an open reading frame of 182 amino acids was identified on the strand corresponding to lambda gt11-40 coding sequences, and those of identical independently isolated cDNA clones defining a 25-kDa surface membrane glycoprotein. The new S. mansoni gene is termed GP22. There are two candidate promoters, confirmed by primer extension studies with worm RNA. Promoter 1 (P1) is preceded by a G + C-rich region and potential CAAT sequences, and is to the 5'-side of P2. Transcription from P1 is initiated at 2 different sites, apparently producing mRNAs with different translation start sites (ATG). Decoding these mRNAs yields protein products of 182 (P1), 175 (P1), 140 (P2) and 136 (P2) amino acids. The polypeptides share the following features: a hydrophobic segment near the carboxy terminus sufficient to span a lipid bilayer, with a consensus sequence for thio-esterification by a fatty acid; an external domain containing 2 potential N-linked glycosylation sites; and a candidate leucine-zipper motif, suggesting the protein may exist as a dimer on the worm surface. While sharing these common features in their carboxy terminal regions, the three proteins differ in the length and properties of their amino termini. The 140-amino acid protein has a short hydrophobic amino terminus, while the 175- and 182-amino acid proteins have more extensive hydrophobic sequences, each preceded by a hydrophilic amino terminal sequence. The heterogeneity observed in 2-dimensional gels of the antigen may be explained in part by the size and charge differences among the proteins deduced from the sequence and transcription pattern of this gene. The possibility of stage-specific regulated expression of this candidate vaccine antigen family is an attractive concept, potentially accounting for the phenomenon of concomitant immunity observed in the rat and perhaps other schistosome hosts.
Mol Biochem Parasitol 1991 Nov
PMID:Cloning and sequence analysis of the Schistosoma mansoni membrane glycoprotein antigen gene GP22. 177 60

BLAST-1 (CD48) (previously referred to as BCM-1 by the Human Gene Nomenclature Committee) is an early-activation-associated membrane glycoprotein expressed on the surface of human leukocytes and induced to a high level following infection of B cells by the Epstein-Barr virus. It is a member of the immunoglobulin superfamily, mediates cell adhesion, and has significant sequence homology to two other adhesion molecules, CD2 and LFA3. Here we report the isolation and characterization of the BLAST-1 gene. The gene is at least 28.6 kb in length, is split into 4 exons, and contains a restriction fragment-length polymorphism. The overall genomic organization is consistent with other members of the immunoglobulin superfamily, in which extracellular immunoglobulinlike domains are encoded by discrete exons. Transcription is initiated at a series of major and minor sites in both normal and tumor-derived lymphoid cells. Appropriately located TATA and CCAAT box sequences were not detected. These characteristics have also been demonstrated for the recently described B-cell-specific genes B29 and CD20. The expression of these genes in B cells may involve the use of multiple promoters and novel transcription initiator-binding proteins. A 1.58-kb genomic DNA fragment, consisting of the 5'-flanking region located immediately upstream of the ATG initiation codon, was able to drive the expression of a reporter gene in an orientation-dependent and tissue-restricted manner.
Mol Cell Biol 1991 Mar
PMID:Characterization of the Epstein-Barr virus-inducible gene encoding the human leukocyte adhesion and activation antigen BLAST-1 (CD48). 184 2

We have used cDNA subtractive cloning to identify a group of human genes that are expressed in diverse differentiated derivatives of neural crest origin but not in neuroblastoma cell lines. One of these genes was identified as CD44, which encodes an integral membrane glycoprotein that serves as the principal receptor for hyaluronate and participates in specific cell-cell and cell-extracellular matrix interactions. The repression of CD44 expression in neuroblastoma cell lines might be relevant to their high metastatic potential. We have cloned full-length cDNAs corresponding to CD44 trancscripts and identified a novel splice variant of CD44 lacking 31 amino acids of the extracellular domain. As a first step toward analysis of CD44 downregulation in neuroblastoma cells, we have mapped the CD44 RNA initiation site and analyzed the structure of the upstream regulatory region. We constructed a series of plasmids containing different amounts of CD44 upstream regulatory region linked to the bacterial chloramphenicol acetyltransferase gene and then analyzed their ability to promote transcription in neuroblastoma and melanoma cells. We found that a DNA segment including about 150 bp of the CD44 upstream region and the 5' end of the gene itself was sufficient to induce substantial transcription of the chloramphenicol acetyltransferase gene in both neuroblastoma and melanoma cells. Several upstream cis-acting elements contribute to the downregulation of CD44 in neuroblastoma cells, the most prominent being a 120-bp DNA fragment located 450 bp upstream to the RNA initiation site. Our data suggest that multiple factors might be involved in downregulation of CD44 in neuroblastoma cells.
Mol Cell Biol 1991 Nov
PMID:Expression of CD44 is repressed in neuroblastoma cells. 192 57

Sec12p is a membrane glycoprotein required for the formation of a vesicular intermediate in protein transport from the endoplasmic reticulum to the Golgi apparatus in Saccharomyces cerevisiae. Comparison of the N-linked glycosylation of Sec12p, a Sec12p-invertase hybrid protein, and a derivative of Sec12p lacking 71 carboxy-terminal amino acids showed that Sec12p is a type II membrane protein. Analysis of two truncated forms of Sec12p and of a temperature-sensitive mutant indicated that the C-terminal domain of Sec12p is not essential for protein transport, whereas the integrity and membrane attachment of the cytoplasmic N-terminal domain are essential. Expression of a soluble cytoplasmic domain dramatically inhibited the growth of a sec12 temperature-sensitive strain by increasing the transport defect at a normally permissive temperature. This growth inhibition as well as the sec12 temperature-sensitive defect were suppressed by the overproduction of Sar1p, a small GTP-binding protein that participates in protein transport. Sar1p membrane association was enhanced by elevated levels of Sec12p. These results suggest that the cytoplasmic domain of Sec12p interacts with Sar1p and that the complex may function to promote vesicle formation.
Mol Cell Biol 1991 Nov
PMID:Structural and functional dissection of a membrane glycoprotein required for vesicle budding from the endoplasmic reticulum. 192 74


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