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)

In GH(1)2C1 rat pituitary cells treated with 5-azacytidine, the stimulatory effects exerted by vasoactive intestinal peptide (VIP), the GTP analogue guanyl-5'-yl imidodiphosphate (Gpp(NH)p), 12-O-tetradecanoyl phorbol 13-acetate, cholera toxin and pertussis toxin on the membrane-bound adenylyl cyclase were almost completely abolished. The corresponding inhibitory effect of somatostatin was increased. Alterations in adenylyl cyclase responsiveness began at the end of the drug treatment, and were most pronounced on day 5 after removal of 5-azacytidine. The cells subsequently and completely recovered after 10 days in the absence of the drug. Measurements of cholera toxin- and VIP-enhanced cyclic AMP levels in intact cells confirmed these results, and VIP appeared to have no stimulatory effect on GH secretion after 5-azacytidine treatment. Down-regulation of G alpha s RNA also occurred on day 5 after cessation of drug treatment. ADP-ribosylation subsequent to stimulation with pertussis toxin was markedly increased, indicating an enhancement of G alpha i and/or G alpha o. Furthermore, both basal and Gpp(NH)p-stimulated phospholipase C activities were augmented by pre-exposure to 5-azacytidine. Treatment of GH(1)2C1 rat pituitary tumour cells with 5-azacytidine therefore causes a marked but temporary increase in the ratio of G alpha i/G alpha s protein levels.
J Mol Endocrinol 1991 Jun
PMID:Signal transduction alterations in GH(1)2C1 rat pituitary tumour cells following treatment with 5-azacytidine. 171 9

We have previously shown that only a single 19-kDa fragment of the Plasmodium falciparum major merozoite surface protein (MSP1) is carried with an invading merozoite into the infected red cell. This fragment (MSP1(19] is derived from the C-terminal membrane-bound end of a major product, MSP1(42), of the primary stage of MSP1 proteolytic processing. Using a monoclonal antibody mapped to an epitope within the N-terminal region of MSP1(42), we have shown that a soluble 33-kDa polypeptide (MSP1(33) corresponding to the N-terminal region of MSP1(42) is shed into culture supernatants during merozoite release and erythrocyte invasion. These observations provide further evidence that the secondary processing of MSP1(42) involves a highly site-specific proteolytic activity.
Mol Biochem Parasitol 1991 Nov
PMID:Processing of the Plasmodium falciparum major merozoite surface protein-1: identification of a 33-kilodalton secondary processing product which is shed prior to erythrocyte invasion. 172 48

We have reported previously that human group C adenoviruses down-regulate the epidermal growth factor (EGF) receptor (EGF-R) (C. R. Carlin, A. E. Tollefson, H. A. Brady, B. L. Hoffman, and W. S. M. Wold, Cell 57:135-144, 1989). Expression of a 13.7-kDa protein encoded by a gene in the E3 transcription unit is necessary and sufficient for this effect (Carlin et al., Cell, 1989; B. L. Hoffman, A. Ullrich, W. S. M. Wold, and C. R. Carlin, Mol. Cell. Biol. 10:5521-5524, 1990). We show here that EGF-R down-regulation is accelerated in cells which overexpress the receptor when these cells are infected with virus mutants that overproduce the 13.7-kDa protein compared with wild-type virus. This is in contrast to EGF stimulation, for which others have shown that high concentrations of ligand are associated with low rates of receptor internalization in EGF-R-overexpressing cells (D. Kuppuswamy and L. J. Pike, J. Biol. Chem. 264:3357-3363, 1989; H. S. Wiley, J. Cell Biol. 107:801-810, 1988). We also show that the E3 protein is not present in media conditioned by infected cells and that it does not induce secretion of an EGF-like autocrine factor. Moreover, while mature membrane-bound EGF-R is down-regulated, the precursor of the membrane-bound form is not. Adenovirus infection also does not affect receptor-related molecules expressed in the secretory pathway. Interestingly, adenovirus-induced down-regulation is not regulated by concentrations of EGF associated with a slow rate of internalization in A431 cells. This suggests that 13.7-kDa protein expression triggers receptor entry by a novel ligand-independent pathway or, alternatively, that it compensates for a cellular factor that may be rate limiting during EGF-mediated endocytosis.
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PMID:Evidence for intracellular down-regulation of the epidermal growth factor (EGF) receptor during adenovirus infection by an EGF-independent mechanism. 172 83

We describe the kinetic modifications to mitochondrial-membrane-bound phosphate-dependent glutaminase in various types of rat tissue brought about by acute metabolic acidosis. The activity response of phosphate-dependent glutaminase to glutamine was sigmoidal, showing positive co-operativity, the Hill coefficients always being higher than 2. The enzyme from acidotic rats showed increased activity at subsaturating concentrations of glutamine in kidney tubules, as might be expected, but not in brain, intestine or liver tissues. Nevertheless, when brain and intestine from control rats were incubated in plasma from acutely acidotic rats enzyme activity increased at 1 mM glutamine in the same way as in kidney cortex. The enzyme from liver tissue remained unaltered. S0.5 and nH values decreased significantly in kidney tubules, enterocytes and brain slices preincubated in plasma from acidotic rats. The sigmoidal curves of phosphate-dependent glutaminase shifted to the left without any significant changes in Vmax. The similar response of phosphate-dependent glutaminase to acute acidosis in the kidney, brain and intestine confirms the fact that enzymes from these tissues are kinetically identical and reaffirms the presence of an ammoniagenic factor in plasma, either produced or concentrated in the kidneys of rats with acute acidosis.
Mol Cell Biochem 1991 Dec 11
PMID:Variations in the kinetic response of several different phosphate-dependent glutaminase isozymes during acute metabolic acidosis. 177 58

The Bordetella pertussis P.69 protein is an immunogen with vaccine potential. The role of this protein in pathogenesis is unclear; it has been associated with the toxic adenylate cyclase and adhesion to eukaryotic cells. For further analysis of the role of P.69 in the biology of B. pertussis, we have constructed strains which specifically lack P.69. The cloned P.69 (prn) gene of B. pertussis was insertionally inactivated with a kanamycin-resistance cassette. This inactivated gene was used to construct P.69- mutants of B. pertussis by allelic exchange using plasmid pRTP1. B. pertussis P.69- strains produced normal levels of other vir-regulated factors, including adenylate cyclase. The serotype of B. pertussis, determined by Eldering and Preston typing sera and monoclonal antibodies, was also unaffected by the presence or absence of P.69. The ability of a prn mutant to adhere to and invade HEp2 cells was not significantly different from that of its parent strain. A strain containing a mutation in fhaB was significantly less adhesive and invasive than its parent, and a prn fhaB double mutant exhibited an even greater reduction in adhesiveness and invasiveness down to levels comparable with a Vir- strain. However, strains harbouring mutations in FHA and/or P.69 were able to colonize or multiply in the murine respiratory tract, although a Vir- strain was unable to survive and proliferate in the same infection model.
Mol Microbiol 1991 Jun
PMID:Construction and characterization of Bordetella pertussis mutants lacking the vir-regulated P.69 outer membrane protein. 178 93

Rapid, quantitative hybridization assays with good sensitivity are needed in many applications, for example, determining the amount of specific product from PCR. We have developed an assay which relies on the hybridization of a biotinylated oligomer and a fluoresceinated oligomer to a single-stranded target in solution. The hybridized complex is captured by streptavidin to a biotinylated membrane. After capture, the hybridization complex is detected by an antifluorescein-urease conjugate which binds to the fluoresceinated probe. The membrane-bound urease conjugate is exposed to urea and assayed with a pH-sensitive silicon sensor. The total assay time is less than 2 h and the sensitivity limit is 20 x 10(6) molecules with a coefficient of variation, CV, of less than 10%. The assay was applied to the analysis of a model target using PCR. We were able to measure the amount of specific product and the amplification factor during the exponential phase of PCR. Using extrapolation from the measured amounts of amplified product, the initial amounts of target molecules were calculated to be 1.2 x 10(6) and 4.0 x 10(2) when the added quantities were 3 x 10(6) and 3 x 10(3), as determined by serial dilution.
Mol Cell Probes 1991 Oct
PMID:Quantitation of DNA hybridization in a silicon sensor-based system: application to PCR. 179 56

The atp operon of Escherichia coli directs synthesis rates of protein subunits that are well matched to the requirements of assembly of the membrane-bound H(+)-ATPase (alpha 3 beta 3 gamma 1 delta 1 epsilon 1a1b2c10-15). Segmental differences in mRNA stability are shown to contribute to the differential control of atp gene expression. The first two genes of the operon, atpl and atpB, are rapidly inactivated at the mRNA level. The remaining seven genes are more stable. It has previously been established that the translational efficiencies of the atp genes vary greatly. Thus differential expression from this operon is achieved via post-transcriptional control exerted at two levels. Neither enhancement of translational efficiency nor insertion of repetitive extragenic palindromic (REP) sequences into the atplB intercistronic region stabilized atpl. We discuss the implications of these results in terms of the pathway of mRNA degradation and of the role of mRNA stability in the control of gene expression.
Mol Microbiol 1991 Oct
PMID:Differential gene expression from the Escherichia coli atp operon mediated by segmental differences in mRNA stability. 183 84

Trichomonas vaginalis homogenates were found to have an acid inorganic pyrophosphatase activity with a specific activity at pH 4.8 of about 7 nmol min-1 (mg protein)-1. This activity was localized predominantly in hydrolase containing particles, showed structure-bound latency and was tightly membrane-bound. The activity showed no magnesium dependence, a Km of about 2 mM inorganic pyrophosphate, a pH optimum of 5.2 and was inhibited by fluoride at millimolar levels. No evidence was obtained for the existence of a cytosolic magnesium-dependent activity but the existence of a low level of magnesium-independent cytosolic activity cannot be excluded. These observations correlate with the importance of cytosolic inorganic pyrophosphate in the carbohydrate catabolism in T. vaginalis.
Mol Biochem Parasitol 1991 Jan
PMID:Inorganic pyrophosphatase of Trichomonas vaginalis. 184 32

As defined by the reaction with monoclonal antibodies, Leishmania mexicana promastigotes contain two acid phosphatases which together comprise about 90% of the cellular activity. A first enzyme recognized by monoclonal antibody AP4 is largely membrane-bound. The protein has an apparent molecular weight of 70,000-72,000, carries about seven N-linked glycan chains and is present in approximately 16,000 copies per cell. The protein is also expressed in the amastigote stage. A second enzyme reactive with monoclonal antibody AP3, that also recognizes lipophosphoglycan and a secreted acid phosphatase, is mainly found in the soluble fraction of promastigote lysates. It is suggested that this enzyme is the precursor of the secreted protein. The N-terminal sequences of the phosphatase recognized by AP4 and the secreted enzyme are similar but not identical. AP4 does not cross-react with phosphatase activity of Leishmania major or Leishmania donovani promastigotes, while AP3 recognizes part of the cellular and all of the secreted phosphatase activity of L. donovani promastigotes but not that of L. major which does not release an acid phosphatase into the culture medium.
Mol Biochem Parasitol 1991 Jul
PMID:Purification and characterization of a membrane-bound acid phosphatase of Leishmania mexicana. 185 78

The major surface glycoprotein of Leishmania, gp63, is a membrane-bound metalloprotease. Contradictory data supporting a neutral or acidic nature of this enzyme have been presented. Seven strains of Old and New World Leishmania, including Leishmania donovani complex (Leishmania infantum and L. donovani), Leishmania major, Leishmania tropica and Leishmania mexicana amazonensis were used for the purification and comparative study of gp63. The protein was extracted from promastigotes by phase separation in Triton X-114 and purified by anion exchange chromatography. In agreement with previous reports, all purified gp63 were found to be structurally and immunologically related. Both membrane-bound gp63, on the surface of promastigotes, and the purified proteases had optimal activity at neutral to alkaline pH on azocasein, whereas their activity was optimal at acidic to neutral pH against 125I-insulin B-chain. The IC50 concentrations of 1,10-phenathroline against the two substrates, at the optimal pH, were comparable, suggesting that both activities measured were associated with gp63 rather than another contaminating enzyme. This was further supported by the comparable enrichment values, estimated from the specific activity of the enzyme during purification, using both assays. These results explain the earlier apparent discrepancies and suggest that the optimum pH of gp63 is substrate-dependent and not related to species differences or to the different purification procedures applied.
Mol Biochem Parasitol 1991 Jul
PMID:Substrate-dependent pH optima of gp63 purified from seven strains of Leishmania. 185 88


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