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 cloned Citrobacter freundii ampC beta-lactamase is inducible in the presence of its regulatory gene ampR in Escherichia coli (Lindberg et al., 1985). The basal level of expression and inducibility are affected by two E. coli proteins encoded by the closely linked ampD and ampE genes. Deletion of both genes led to constitutive ampR-dependent overproduction of beta-lactamase, whereas an out-of-frame deletion in AmpD caused the basal expression to increase two-fold. This ampD1 mutant was inducible at lower beta-lactam concentrations than the wild type. An IS1 insertion in ampD was polar on ampE expression and increased basal beta-lactamase expression 30-fold while mediating a semi-constitutive phenotype. AmpE expressed from a recombinant plasmid in an ampD-ampE deletion mutant reduced basal beta-lactamase expression to wild-type levels but did not markedly reduce beta-lactam resistance since the cells became hyperinducible. In the absence of AmpD, increasing levels of AmpE therefore decrease the basal expression of AmpC beta-lactamase in an AmpR-dependent manner. AmpD modulated the response exerted on beta-lactamase expression by AmpE. The ampD gene encodes a 20.5kD cytoplasmic protein while the 32.1kD ampE gene product is an integral membrane protein with a likely ATP-binding site between the second and third putative transmembrane region. Since neither AmpD nor AmpE are needed for beta-lactam induction and since these proteins could not be covalently labelled by benzylpenicillin, they are not thought to act as beta-lactam-binding sensory transducers. Instead it is suggested that AmpD and AmpE sense the effect of beta-lactam action on peptidoglycan biosynthesis and relay this signal to AmpR.
Mol Microbiol 1989 Aug
PMID:Signalling proteins in enterobacterial AmpC beta-lactamase regulation. 269 40

We describe the cloning of a novel antigen of Plasmodium falciparum which contains a hydrophobic domain typical of an integral membrane protein. This antigen is designated apical membrane antigen 1 because it appears to be located in the apical complex. Apical membrane antigen 1 appears to be transported to the merozoite surface near the time of schizont rupture.
Mol Cell Biol 1989 Jul
PMID:Integral membrane protein located in the apical complex of Plasmodium falciparum. 270 47

The nerve growth factor (NGF) receptor is an integral membrane protein that is phosphorylated and heavily glycosylated. Determination of the amino acid sequence by molecular cloning indicates that the receptor is a cysteine-rich protein which contains a signal peptide sequence and spans the lipid bilayer with a single transmembrane sequence. A single mRNA of 3.8 kilobases was observed for the receptor, of which 1.5 kilobases is coding sequence. We have used microinjection of receptor RNA in Xenopus laevis oocytes to obtain cell surface expression of the receptor. The presence of NGF receptors in oocytes was verified by radioimmunoassay, specific binding of [125I]NGF, and metabolic labeling followed by immunoprecipitation. The NGF receptor protein was rapidly processed in oocytes and displayed extensive glycosylation. Furthermore, the presence of NGF receptors in oocytes potentiates the ability of progesterone to induce maturation.
Mol Cell Biol 1988 May
PMID:Efficient processing and expression of human nerve growth factor receptors in Xenopus laevis oocytes: effects on maturation. 283 43

Subgenomic mRNA from a virulent isolate of porcine transmissible gastroenteritis virus (TGEV) was used to produce cDNA clones. Part of a new clone and a previously reported clone were sequenced and used to construct the viral gene for integral membrane protein. A single open reading frame (ORF) encoding a polypeptide of 262 amino acids, relative molecular mass (Mr) 29,459, was identified. The positive identification of the polypeptide as the integral membrane protein was demonstrated by the production in E. coli of a chimaeric protein comprising most of the ORF encoding the Mr 29,459 polypeptide and beta-galactosidase. The chimaeric protein reacted with a specific monoclonal antibody to viral integral membrane protein and antibodies raised against the chimaeric protein immune precipitated the viral protein. Comparison with the sequence of an avirulent isolate indicates amino acid residues that may be important in pathogenicity.
Mol Microbiol 1988 Jul
PMID:The integral membrane protein from a virulent isolate of transmissible gastroenteritis virus: molecular characterization, sequence and expression in Escherichia coli. 284 26

The membrane orientation of the NB protein of influenza B virus, a small (Mr, approximately 18,000) glycoprotein with a single internal hydrophobic domain, was investigated by biochemical and genetic means. Cell fractionation and protein solubility studies indicate NB is an integral membrane protein, and NB has been shown to be a dimer under nonreducing conditions. Treatment of infected-cell surfaces with proteinase K and endoglycosidase F and immunoprecipitation with a site-specific antibody suggests that the 18-amino-acid NH2-terminal region of NB is exposed at the cell surface. Oligonucleotide-directed mutagenesis to eliminate each of the four potential sites of N-linked glycosylation and expression of the mutant NB proteins in eucaryotic cells suggest that the two sites adjacent to the NH2 terminus are glycosylated. This provides further evidence that NB, which lacks a cleavable NH2-terminal signal sequence, has an exposed NH2 terminus at the cell surface.
Mol Cell Biol 1986 Dec
PMID:Determination of the orientation of an integral membrane protein and sites of glycosylation by oligonucleotide-directed mutagenesis: influenza B virus NB glycoprotein lacks a cleavable signal sequence and has an extracellular NH2-terminal region. 302 52

The Simian 11 rotavirus glycoprotein VP7 is directed to the endoplasmic reticulum (ER) of the cell and retained as an integral membrane protein. The gene coding for VP7 predicts two potential initiation codons, each of which precedes a hydrophobic region of amino acids (H1 and H2) with the characteristics of a signal peptide. Using the techniques of gene mutagenesis and expression, we have determined that either hydrophobic domain alone can direct VP7 to the ER. A protein lacking both hydrophobic regions was not transported to the ER. Some polypeptides were directed across the ER membrane and then into the secretory pathway of the cell. For a variant retaining only the H1 domain, secretion was cleavage dependent, since an amino acid change which prevented cleavage also stopped secretion. However, secretion of two other deletion mutants lacking H1 and expressing truncated H2 domains was unaffected by this mutation, suggesting that these proteins were secreted without cleavage of their NH2-terminal hydrophobic regions or secreted after cleavage at a site(s) not predicted by current knowledge.
Mol Cell Biol 1987 Jul
PMID:Location of sequences within rotavirus SA11 glycoprotein VP7 which direct it to the endoplasmic reticulum. 303 47

The structure of thin three-dimensional crystals of the light-harvesting chlorophyll a/b protein complex, an integral membrane protein from the photosynthetic membrane of chloroplasts, has been determined at 7 A (1 A = 0.1 nm) resolution in projection. The structure analysis was carried out by image processing of low-dose electron micrographs, and electron diffraction of thin three-dimensional crystals preserved in tannin. The three-dimensional crystals appeared to be stacks of two-dimensional crystals having p321 symmetry. Results of the image analysis indicated that the crystals were disordered, due to random translational displacement of stacked layers. This was established by a translation search routine that used the low-resolution projection of a single layer as a reference. The reference map was derived from the symmetrized average of two images that showed features consistent with the projected structure of negatively stained two-dimensional crystals. The phase shift resulting from the displacement of each layer was corrected. Phase shifts were then refined by minimizing the phase residual, bringing all layers to the same phase origin. Refined phases from different images were in agreement and reliable to 7 A resolution. A projection map was generated from the averaged phases and electron diffraction amplitudes. The map showed that the complex was a trimer composed of three protein monomers related by 3-fold symmetry. The projected density within the protein monomer suggested membrane-spanning alpha-helices roughly perpendicular to the crystal plane. The density in the centre and on the periphery of the trimeric complex was lower than that of the protein, indicating that this region contained low-density matter, such as lipids and antenna chlorophylls.
J Mol Biol 1988 Aug 20
PMID:Structure of light-harvesting chlorophyll a/b protein complex from plant photosynthetic membranes at 7 A resolution in projection. 305 Jan 33

A hypothetical structure of the glycolytic enzyme complex (glycolytic metabolon) adsorbed on the inner surface of the erythrocyte membrane has been proposed. Oligomers of integral membrane protein, band 3 protein (anion-transport system), are the anchor site for the complex. The complex is supposed to have a three-fold symmetry axis, perpendicular to the membrane plane, and contains a triple set of the glycolytic enzymes. The complex is in equilibrium with free enzymes; the equilibrium state depends on the physiological state of the erythrocyte.
Mol Biol (Mosk)
PMID:[Hypothetical structure of the glycolytic enzyme complex (glycolytic metabolon) formed on erythrocyte membranes]. 307 64

The biogenesis of hamster brain prion protein (PrP) has been studied by expression of RNA transcribed from a full-length PrP cDNA in Xenopus oocytes and cell-free systems. Earlier studies in the wheat germ cell-free system showed that one form of PrP is a transmembrane protein that spans the bilayer at least twice [Hay, B., Barry, R. A., Lieberburg, I., Prusiner, S. B., & Lingappa, V. R. (1987) Mol. Cell. Biol. 7, 914-920]. We now report that PrP can also exist as a secreted protein. SP6 PrP RNA microinjected into Xenopus oocytes produced two forms of PrP: one that remained in the cell and another that was secreted into the medium. Cell-free translation studies in rabbit reticulocyte lysates supplemented with microsomal membranes gave similar results: while one form of PrP was found as an integral membrane protein spanning the membrane at least twice, another form of PrP was found to be completely translocated to the microsomal membrane vesicle lumen. Both the membrane and secretory forms of PrP appear to be generated from the same pool of nascent chains. The mechanism governing the alternative fates of nascent PrP remains to be elucidated but may have significance for understanding the pathogenesis of scrapie and other prion diseases.
 ...
PMID:Evidence for a secretory form of the cellular prion protein. 312 96

Triton X-114 has been employed to isolate integral membrane proteins from Schistosoma japonicum and Schistosoma mansoni adult worms. Suitable marker molecules and antisera directed or raised against schistosome proteins partitioned by Triton X-114 extraction indicated that the phase separation and purification of integral membrane proteins had been successful and this fraction was free of contamination with aqueous (soluble) or secretory antigens. Two dimensional immunoblots further exemplified differences between antigens in the integral membrane protein extract and those of the aqueous fraction. Seven S. japonicum integral membrane proteins have been identified on immunoblots by serum from a hyperimmune and an infected rabbit and by sera from Philippine patients with a history of schistosomiasis japonica. Integral membrane proteins of S. mansoni and S. japonicum had surprisingly little conformity in the molecular weights and electrophoretic mobilities between the two species.
Mol Biochem Parasitol 1988 May
PMID:Immunoblotting analysis of the major integral membrane protein antigens of Schistosoma japonicum. 313 62


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