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)

Recombinant HIV-1 reverse transcriptase (RT) was stably overproduced as a soluble protein in Escherichia coli using a double-plasmid expression system in which an RT precursor protein was expressed and processed in vivo by HIV-1 protease produced in trans. The RT thus produced consisted of an equimolar mixture of two polypeptides, p66 and p51, which were copurified to greater than 90% homogeneity and were found to share a common NH2 terminus as judged by sequence analysis of the polypeptide mixture. The observed sequence confirmed correct in vivo cleavage by protease at the protease-RT polyprotein junction to yield an NH2 terminus identical to that of genuine viral RT (M. M. Lightfoote et al. (1986) J. Virol. 60, 771-775; F. diMarzo Veronese et al. (1986) Science 231, 1289-1291). The bacterially expressed RT had a specific activity similar to that of viral RT and inhibition studies with phosphonoformate confirmed that it was indistinguishable from the viral enzyme with respect to sensitivity to this inhibitor. Polymerase activated gel analysis of the mixture indicated that p66 was associated with a higher level of RT activity than p51. RNase H activated gel analysis suggested that the purified preparation of recombinant RT was free of endogenous E. coli RNase H, and that the RNase H activity of RT was exclusively associated with the p66 polypeptide, supporting the hypothesis that the RNase H domain is located in the COOH-terminal region of the molecule.
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PMID:Recombinant HIV-1 reverse transcriptase: purification, primary structure, and polymerase/ribonuclease H activities. 247 69

The neuritic plaque is a characteristic finding in Alzheimer's disease. A major component of the plaque core is a 4.2 kd polypeptide, amyloid beta-protein (ABP), which is derived from the C-terminus of a larger precursor protein (ABPP). The authors have studied the transcription of ABPP mRNA in the adult rat brain by Northern analysis and in situ hybridization, and report that the ABPP gene gives rise to essentially the same multitranscript family of mRNAs as in the human, and that differential transcription patterns exist between brain and kidney. Morphologically, ABPP mRNA is expressed ubiquitously in neurons of the fore and hindbrain. ABPP transcripts also are present less frequently in occasional glial cells and at moderate to low frequency in nonneural cell types, namely, the choroid plexus epithelium, ependymal cells, and leptomeningeal membranes. Neuronal transcripts are most abundant in cerebral cortical layers II and V, the pyramidal cell layer of the hippocampus, the olfactory cortex, nucleus basis pontis, cranial nerve nuclei, and, significantly, in Purkinje cells and cerebellar granule cells. Because the cerebellum is relatively uninvolved in Alzheimer's disease, these findings suggest that high intraneuronal expression of ABPP may be a necessary but not sufficient requirement for plaque formation.
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PMID:Widespread expression of amyloid beta-protein precursor gene in rat brain. 250 26

A murine interleukin-1 alpha (mIL-1 alpha) gene coding for amino acids 115 to 270 of the precursor protein (Lomedico, P.T., Gubler, U., Hellmann, C.P., Dukovich, M., Giri, J.G., Pan, Y.E., Collier, K., Semionow, R., Chua, A.O. and Mizel, S.B. (1984) Nature 312, 458-462) was chemically synthesized and expressed in Escherichia coli. mIL-1 alpha, in the form of insoluble inclusion bodies, accounted for approx. 30% of total cellular protein produced by the recombinant strain. A simple isolation protocol was developed in which inclusion body material was first solubilized in 3 M guanidine hydrochloride, and the mIL-1 alpha was then simultaneously purified and allowed to fold to its active conformation by dialysis against distilled water. This procedure yielded pure, biologically active mIL-1 alpha with 41% recovery of the mIL-1 alpha present in the guanidine hydrochloride extract. The purified preparation had the expected amino acid composition, a molar absorptivity of 28,200 M-1.cm-1 and a pI of 5.2. No methionyl-mIL-1 alpha was detected by N-terminal sequence analysis, and the endotoxin level was less than 10 pg per micrograms of mIL-1 alpha. The specific biological activity was 3.10(7) units/mg in a co-mitogenic thymocyte proliferation assay. In addition to full-length mIL-1 alpha, the preparation contained N-terminally truncated mIL-1 alpha species (mainly des-4 and des-6 amino acid forms). The truncated species were isolated and found to have the same biological activity as the complete polypeptide. Thus, the active fragment of mIL-1 alpha appears to consist of a proteinase-sensitive N-terminal region which is not essential for activity, and a proteinase-resistant core which harbors the essential determinants of its cytokine function.
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PMID:Isolation and characterization of biologically active murine interleukin-1 alpha derived from expression of a synthetic gene in Escherichia coli. 255 91

The structure of ATP synthase subunit 4 was determined by using the oligonucleotide probe procedure. This subunit is the fourth polypeptide of the complex when classifying subunits in order of decreasing molecular mass. Its relative molecular mass is 25 kDa. The ATP4 gene was isolated and sequenced. The nucleotide sequence predicts that subunit 4 is probably derived from a precursor protein 244 amino acids long. Mature subunit 4 contains 209 amino acid residues and the predicted molecular mass is 23250 kDa. Subunit 4 shows homology with the b-subunit of Escherichia coli ATP synthase and the b-subunit of beef heart mitochondrial ATP synthase. By using homologous transformation, a mutant lacking wild subunit 4 was constructed. This mutant is devoid of oxidative phosphorylation and F1 is loosely bound to the membrane. Our data are in favor of a structural relationship between subunit 4 and the mitochondrially-translated subunit 6 during biogenesis of F0.
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PMID:The yeast ATP synthase subunit 4: structure and function. 255 30

A full-length cDNA clone for the 24S subgenomic mRNA of the vaccine strain (HPV77) of rubella virus has been isolated from a cDNA library made from the RNAs of infected cells. Starting from the first Met start codon, the 24S mRNA codes for a precursor protein of 1063 amino acids (aa). This precursor encodes a capsid protein of 300 aa, and two envelope proteins, E1 (481 aa) and E2 (282 aa). Both the E1 and E2 proteins are preceded by a stretch of 21 hydrophobic aa, characteristic of a signal peptide, and each has three putative glycosylation sites in the polypeptide chains. Comparison between the structural proteins of the vaccine and the wild-type (wt; M33) strains of rubella virus, revealed that the E2 protein of the vaccine strain differs, in its apparent Mr, by approx. 3 kDa, from the wt strain. The difference could be due to decreased glycosylation of the vaccine strain E2 protein, as revealed by [3H]mannose incorporation studies. Five single-aa changes in the structural proteins occurred during the attenuation process, one each in the capsid and the E1 protein and three in the E2 protein. The change of Thr-412----Ile in the E2 protein results in the loss of a putative glycosylation site at Asn-410, which offers a plausible explanation for decreased glycosylation of the E2 protein from the vaccine strain of rubella virus.
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PMID:Nucleotide sequence of the 24S subgenomic messenger RNA of a vaccine strain (HPV77) of rubella virus: comparison with a wild-type strain (M33). 258 26

The genomic RNAs of aphid lethal paralysis virus (ALPV) and Rhopalosiphum padi virus (RhPV)--two distinct picorna-like viruses found in aphids [Williamson et al. (1988) J Gen Virol 69: 787-795]--were both efficiently translated in rabbit reticulocyte lysates. ALPV RNA was translated into primary products with molecular weights ranging from 92 kDa to 170 kDa. These underwent time-dependent post-translational cleavage to produce smaller polypeptides including some with molecular weights comparable to those of the viral structural proteins. A 92 kDa polypeptide as well as smaller proteins were immunoprecipitated with capsid protein antisera, indicating the presence of at least one large capsid subunit protein precursor. RhPV RNA was translated into products of molecular weights ranging from 45 kDa to 175 kDa. There was no evidence for time-dependent post-translation cleavage of RhPV translation products. However, a 60 kDa polypeptide was precipitated with antiserum to RhPV virions, indicating that at least one capsid protein of RhPV is derived by proteolysis of a precursor protein, like those of ALPV and most other picornaviruses.
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PMID:A comparative study on the cell-free translation of the genomic RNAs of two aphid picorna-like viruses. 261 May 97

The relationship between the length of the connecting peptide in a paramyxovirus F0 protein and cleavage of F0 into the F1 and F2 subunits has been examined by constructing a series of mutant F proteins via site-directed mutagenesis of a cDNA clone encoding the simian virus 5 F protein. The mutant F proteins had one to five arginine residues deleted from the connecting peptide. The minimum number of arginine residues required for cleavage-activation of the simian virus 5 F0 protein by host cell proteases was found to be four. F proteins with two or three arginine residues in the connecting peptide were not cleaved by host cell proteases but could be cleaved by exogenously added trypsin. The mutant F protein possessing a connecting peptide consisting of one arginine residue was not cleaved by trypsin. The altered F proteins were all transported to the infected-cell plasma membrane as shown by cell surface immunofluorescence or cell surface trypsinization. However, the only mutant F protein found to be biologically active as detected by syncytium formation was the F protein which has four arginine residues at the cleavage site. The results presented here suggest that in the paramyxovirus F protein the number of basic amino acid residues in the connecting peptide is important for cleavage of the precursor protein by host cell proteases but is not the only structural feature involved. In addition, the data indicate that cleavage of F0 into F1 and F2 does not necessarily result in biological activity and that the connecting peptide may affect the local conformation of the F polypeptide.
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PMID:Analysis of the relationship between cleavability of a paramyxovirus fusion protein and length of the connecting peptide. 264 48

The actual presence of the predicted precursor of Alzheimer's disease amyloid A4 protein, reported by Kang et al. (1987) in the Alzheimer brain, has yet to be verified. To identify the various regions of this precursor, antibodies were raised against three synthetic polypeptides, R35 (residues 274-286), R36 (residues 527-540), and R37 (residues 681-695), subsequences of the precursor protein; the specificity of these antibodies was ascertained by ELISA. Upon immunohistochemical examination, the antibody to R35 failed to react, but the antibody to R36 (the extracellular part) stained the amyloid of senile plaques and the staining pattern was identical to that of anti-A4 antibody. The antibody to R37 (the C-terminal intracellular part) stained what may be degenerating neurites in senile plaques whereas the amyloid remained unstained. An anti-neurofilament (NF) antibody reacted with some of the R37-positive grains, but R37-negative grains also were seen. Further, some R37-positive grains were not stained by the anti-NF antibody. The anti-GFAP antibody and the anti-macrophage antibody did not stain the R37-positive grains. These findings indicate that the amyloid protein in senile plaques actually contains a larger polypeptide than the A4 protein, and suggest that the intracellular C-terminal part of the precursor may exist in the degenerated neurites seen in senile plaques.
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PMID:The immunohistochemical demonstration of subsequences of the precursor of the amyloid A4 protein in senile plaques in Alzheimer's disease. 265 71

Conformations of an artificial mitochondrial precursor protein pCox IV-DHFR have been analyzed by CD and fluorescence spectroscopy in the presence of (cardiolipin-rich) phospholipid vesicles or SDS micelles. Binding of pCox IV-DHFR to phospholipid vesicles involves a conformational change, which is presequence-dependent, accompanies alteration in the secondary structure of the DHFR moiety, but is different from total unfolding of the polypeptide chain. On the other hand, a conformational change of the fusion protein on binding to the micelles of a positively charged detergent, SDS, is not presequence-dependent.
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PMID:Conformational changes of a mitochondrial precursor protein on binding to phospholipid vesicles and SDS micelles. A circular dichroism and fluorescence spectroscopy study. 266 Dec 63

A newly discovered macrophage-chemotactic factor (MCFS-1) was extracted and purified (488-fold) from skin sites of guinea pigs showing delayed hypersensitivity to bovine gamma-globulin. MCFS-1 is a heat-labile glycoprotein with a molecular weight of 150,000, consisting of two polypeptide chains. It has in vivo as well as in vitro chemotactic activity for macrophages and shared 50% of the chemotactic activities for macrophages in the extract. It is produced by limited proteolysis of endogenous trypsin-like protease(s) of plasma precursor protein (Pre-MCFS-1). Enzyme immunohistochemistry reveals that Pre-MCFS-1 is produced in the liver and distributed in the normal skin as a proinflammatory factor. ELISA reveals that the concentrations of the factor are: 140 micrograms/ml in plasma, 7.1 micrograms/ml in inflamed skin extract, and 2.8 micrograms/ml in normal skin extract.
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PMID:Chemotactic factors for macrophages produced in inflamed skin. 267 55


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