Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The biosynthesis and biochemical characteristics of the 39,000 cell surface glycoprotein detected by Mab 41H.16 were investigated. Experiments utilizing tunicamycin, endoglycosidase H, endoglycosidase F and N-glycosidase F indicate that the mature molecule expressed at the cell surface is composed largely of N-linked oligosaccharides of both the complex and high mannose types. When synthesized in the presence of tunicamycin, the molecule appeared on the cell surface with a Mr of 32,000. Digestion with both endoglycosidase H and endoglycosidase F yielded a single band of Mr 37,000. Parallel experiments with N-glycosidase F revealed species of approx. 35,000 and 32,000. Synthesis in the presence of monensin yielded a 37,500 product. [3H]Glucosamine and [3H]mannose were incorporated into the molecule but no evidence for fucose incorporation could be found. Microheterogeneity of gp39 with respect to Mr and oligosaccharide structure was demonstrated by biosynthetic labelling and lectin chromatography. Biosynthetic pulse-chase labelling showed that the de novo synthesis of the 39,000 molecule occurs without detectable precursor formation. Results of temperature-dependent phase separation experiments were consistent with gp39 being an integral membrane protein. Two-dimensional electrophoresis showed heterogeneity of the isoelectric points associated with the N-linked oligosaccharides. Galactose oxidase/NaB[3H]4 labelling showed that a terminal sialic acid protects a galactose residue. All results are consistent with the conclusion that the gp39 molecule is an integral membrane glycoprotein composed of heterogeneous N-linked oligosaccharides of both the complex and high mannose types.
Mol Immunol 1988 Sep
PMID:Characterization of gp39, a B-lymphocyte associated differentiation antigen which is also present on granulocytes and macrophages. 326 83

The nucleotide sequence of the structural gene, scrA, which codes for sucrose-specific EnzymeII(Scr) (EII(Scr)) of the phosphoenolpyruvate-dependent carbohydrate:phosphotransferase system (PTS), was determined. EllScr requires an EnzymeIII, the product of the gene crr, for full activity. The gene scrA is preceded immediately by a classical Shine-Dalgarno sequence (AAGAGGGTA). It contains 1368 nucleotides with an increased GC-content (58%) corresponding to a polypeptide of 455 amino acid residues (Mr 47,500). The protein has the hydropathic profile (average hydropathy +0.82) of an integral membrane protein lacking extended alpha-helical structures and a signal peptide. Comparison with the sequence of the beta-glucoside-specific EnzymeII (EII(Bgl), 625 amino acids, Mr 66,480; Bramley and Kornberg, 1987a; Schnetz et al., 1987) revealed strong homologies between EiI(Scr) and the first 458 residues of EII(Bgl). The 162 carboxyterminal residues of EII(Bgl), however, showed a high homology with the sequence of EnzymeIII (Nelson et al., 1984), a homology also described recently by Bramley and Kornberg (1987b). The evolutionary and functional significance of the similarities with four other EnzymesII is discussed.
Mol Microbiol 1988 Jan
PMID:DNA sequence of the gene scrA encoding the sucrose transport protein EnzymeII(Scr) of the phosphotransferase system from enteric bacteria: homology of the EnzymeII(Scr) and EnzymeII(Bgl) proteins. 328 23

Attempts to construct hybrid proteins that are transported to the plasma membrane are frequently unsuccessful because of perturbations in polypeptide folding. In seeking to minimize this problem, we have used the less common type of integral membrane protein, which has an uncleaved signal-anchor domain and an extracellular carboxyl portion, to transport a peptide sequence of interest to the cell surface. A set of plasmids was constructed that contained the gene encoding respiratory syncytial virus glycoprotein G (RSVG) interrupted immediately after one of several proline codons by a synthetic sequence containing unique restriction endonuclease sites and a stop codon. The shortened RSVG gene was flanked by vaccinia virus DNA to permit cloning and expression in a vaccinia virus vector. An open reading frame encoding four copies of the immunodominant repeating epitope of the circumsporozoite protein of Plasmodium falciparum was inserted into the tails of the truncated RSVG genes. Recombinant vaccinia viruses were isolated and shown to express hybrid proteins that reacted with a monoclonal antibody directed to the repeating circumsporozoite epitope. Moreover, immunofluorescence studies indicated that the peptide was on the external cell surface and available to react with antibodies. Expression of the hybrid protein also occurred in rabbits inoculated with the live recombinant vaccinia virus, as demonstrated by the generation of antibodies that bound to P. falciparum sporozoites in vitro.
Mol Cell Biol 1988 Apr
PMID:Transport to the cell surface of a peptide sequence attached to the truncated C terminus of an N-terminally anchored integral membrane protein. 338 95

The recently described adherens junction-specific 135-kD protein (Volk, T., and B. Geiger, 1984, EMBO (Eur. Mol. Biol. Organ.) J., 3:2249-2260) was localized along cardiac muscle intercalated discs by immunogold labeling of ultrathin frozen sections. Analysis of this labeling indicated that the 135-kD protein, adherens junction-specific cell adhesion molecule (A-CAM), is tightly associated with the plasma membrane unlike vinculin labeling, which was present along the membrane-bound plaques of the fascia adherens. In cultured chick lens cells, A-CAM was associated with Ca2+-dependent junctions that were cleaved upon a decrease of extracellular Ca2+ concentrations to less than or equal to 0.5 mM. In the chelator-separated junction, A-CAM became exposed to exogenously added antibodies or to proteolytic enzymes. Upon addition of trypsin to EGTA-treated cells, A-CAM was cleaved into three major cell-bound antigenic peptides with apparent molecular masses of 78, 60, and 46 kD, suggesting that the extracellular domain of A-CAM has a size greater than or equal to kD. Incubation of electrophoretic gels with 125I-concanavalin A (Con A) indicated that one of the major Con A-binding proteins in chicken lens membranes is a integral of 135-kD glycoprotein that was partially purified on Con A-Sepharose column and identified as A-CAM by immunoblotting. Detergent partitioning assay using Triton X-114 biphasic system was carried out to determine whether A-CAM displays properties of an integral membrane protein. This assay indicated that the intact A-CAM molecule was recovered in the buffer phase but its cell-associated tryptic peptides, which presumably lost a great part of the A-CAM extracellular extension, readily partitioned into the detergent phase. The results obtained in this and in the following paper (Volk, T., and B. Geiger, 1986, J. Cell Biol., 103:1451-1464) strongly suggest that A-CAM is a Ca2+-dependent adherens junction-specific membrane glycoprotein that is involved in intercellular adhesion in these sites.
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PMID:A-CAM: a 135-kD receptor of intercellular adherens junctions. I. Immunoelectron microscopic localization and biochemical studies. 353 54

We describe a detailed deletion analysis of the anchoring domain of a model membrane protein. Removal of the 23 contiguous uncharged amino acids from the carboxy terminus of the bacteriophage fl gene III protein (pIII) converts it from an integral membrane protein to a secreted periplasmic form. Deletions that remove six or fewer residues of the hydrophobic core result in no diminution of the protein's capacity to anchor in the membrane. Longer deletions into this hydrophobic domain gradually destablize the protein-membrane association. pIII derivatives with over half of the hydrophobic core deleted retain substantial residual anchor function. The basic residues, arginine and lysine, which provide a carboxy-terminal boundary for this domain, can be deleted without loss of anchoring capacity.
J Mol Biol 1985 Jan 05
PMID:Fine structure of a membrane anchor domain. 387 73

The complete DNA sequence of the CAN1 locus of the yeast Saccharomyces cerevisiae is presented. The predicted primary translation product consists of 590 amino acids. From the hydropathic profile of the amino acid sequence (as calculated by the algorithm of Kyte and Doolittle (Kyte, J., and Doolittle, R. F. (1982) J. Mol. Biol. 157, 105-132)), one can divide the protein into two distinct regions. The 93-amino acid long N-terminal domain is extremely hydrophilic and does not exhibit any cleavable signal sequence. The rest of the protein (from amino acids 94 to 590) shows features typical for an integral membrane protein. The proposal for the N terminus of the primary translation product is based on results obtained by S1 mapping, insertion mutagenesis, and gene fusion experiments.
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PMID:Molecular characterization of the CAN1 locus in Saccharomyces cerevisiae. A transmembrane protein without N-terminal hydrophobic signal sequence. 390 64

Promastigotes of Leishmania major LRC-L137, L. donovani LEM 75, and L. tropica LRC-L32 were surface radioiodinated. The proteins of the parasites were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and labeled molecules were revealed by fluorography. A single major iodinated protein of Mr 63 000 (p63) was identified in each of the three species. These proteins were partially purified by phase separation in Triton X-114 solution, demonstrating that the p63 of each of the three species is the most abundant integral membrane protein in the promastigote. Peptide maps were obtained by partial proteolysis with N-chlorosuccinimide or Staphylococcus V8 protease followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The maps of L. major and L. donovani were identical, but only partially homologous to the maps of L. tropica p63. Finally, immunological crossreactivity among the three p63s was demonstrated with the serum of a mouse immunized with purified L. major p63, and the serum of a dog naturally infected with L. donovani. The data show that the major surface proteins found on promastigotes of three Old World Leishmania species are structurally related.
Mol Biochem Parasitol 1985 Feb
PMID:Evidence that the major surface proteins of three Leishmania species are structurally related. 399 Jul 4

An integral membrane protein forming channels across Escherichia coli outer membranes, porin, has been crystallized using a polyethylene glycol or salt-generated two-phase system. Monodispersity and homogeneity of protein-detergent complexes were found to be prerequisites for reproducible formation of crystals amenable to X-ray structural analysis. By varying pH, detergent and buffer type, large crystals of three different habits can be obtained, two of which are discussed in this paper. The tetragonal form (space group P4(2); unit cell dimensions, a = b = 155 A, c = 172 A) is suitable for X-ray analysis. Low temperature induces a change of the space group to P4(2)22, with a single trimer in the asymmetric unit. This crystal form diffracts to a resolution beyond 2.9 A. The hexagonal crystal form (space group P6(3)22; unit cell dimensions, a = b = 93 A, c = 220 A) is limited in resolution to 4.5 A, but reveals a packing arrangement very similar to that in two-dimensional membrane-like crystalline arrays.
J Mol Biol 1983 Feb 25
PMID:X-ray diffraction analysis of matrix porin, an integral membrane protein from Escherichia coli outer membranes. 630 73

Investigations in numerous laboratories have characterized a salt transport system, present in many animal cell types, which catalyzes the transmembrane transport of NaCl and KCl in a tightly coupled process. The system is inhibited by loop diuretics such as furosemide and bumetanide. This transport system has been designated the loop diuretic-sensitive NaCl/KCl symporter. It has been implicated in transepithelial salt secretion and absorption as well as in cell volume regulation, and it may be defective in patients suffering from essential hypertension. This review serves to evaluate research conducted to date regarding the mechanism, mode of regulation, and physiological significance of the transport system. Ion binding specificities and absolute binding constants for all three naturally occurring ions have been determined in one cell system, the MDCK kidney epithelial cell line. In that same cell line, substrate binding was shown to exhibit apparent cooperativity. although a few reports suggest unidirectional transport of ions via this system under certain conditions, the consensus of reports indicates fully reversible, bidirectional salt transport with the direction of net flux determined by the magnitudes of the gradients of the three transported ions. Growth of cells in media containing a low concentration of K+ (less than 0.25 mM) allows selection of mutants lacking or defective in the symporter. Kinetic analyses with the MDCK cell line have shown that the symporter catalyzes accelerative exchange transport. However, exchange transport of one ion in the absence of one of the other two ionic substrates has not been documented. Comparison with other well-characterized transmembrane transport systems has shown that the characteristics of the NaCl/KCl symporter most resemble those of two-species facilitators (chemiosmotically-coupled symporters) found in prokaryotes and eukaryotes alike. these two-species facilitators consist of a single transmembrane protein and may function by a carrier-type mechanism as originally proposed by Peter Mitchell. A molecular model for the NaCl/KCl symporter is presented and discussed. Activation of symport activity requires ATP and probably occurs by a protein kinase-catalyzed mechanism. In some cell types activation is cyclic AMP dependent. ATP hydrolysis is not stoichiometric with transport. Phosphorylation of an integral membrane protein with an apparent size of 240 000 daltons correlates with activation of transport. It is postulated that this protein is the loop diuretic-sensitive NaCl/KCl symporter.
Mol Cell Biochem 1984
PMID:Mechanism, regulation and physiological significance of the loop diuretic-sensitive NaCl/KCl symport system in animal cells. 632 61

Circular dichroic measurements on the lac carrier protein purified from the cytoplasmic membrane of Escherichia coli indicate that 85 +/- 5% of the amino acid residues comprising this integral membrane protein are arranged in helical secondary structures. Analysis of the sequential hydropathic character of this protein by the method of Kyte and Doolittle (J. Mol. Biol. (1982) 157, 105-132) indicates that the protein is composed of at least 12 hydrophobic segments with a mean length of 24 +/- 4 residues/segment. Approximately 70% of the 417 amino acids in the lac carrier are found in these domains. The hydropathic profile, together with the circular dichroic measurements, suggest that the 12 hydrophobic segments are largely in a helical conformation. If the segments are assumed to be alpha-helical, the mean length of each domain approximates the thickness of the most hydrophobic portion of the lipid bilayer. Based on these considerations, it is proposed that the lac carrier protein consists of at least 12 alpha-helical segments that traverse the membrane in a perpendicular sense, i.e. in a fashion similar to bacteriorhodopsin.
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PMID:Structure of the lac carrier protein of Escherichia coli. 633 50


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