Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.5.1.18 (glutathione S-transferase)
 22,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have characterized the expression of a baculoviral gene, ptp, and determined the location of its gene product, a protein tyrosine/serine phosphatase (BV-PTP), during virus infection. Using an antibody raised to a BV-PTP fusion to glutathione S-transferase, we found that ptp was expressed as a 19 kDa polypeptide at late times during virus infection. However, we also found that BV-PTP was present in the virions of both the budded and occluded forms so that a low level of BV-PTP is also present at the beginning of the infection process. Biochemical fractionation also showed that BV-PTP was primarily localized to the cytoplasm in transfected cells but that BV-PTP was present in both the cytoplasm and the nucleus of baculovirus-infected cells. Immunoelectron microscopy revealed that BV-PTP was associated with fibrillar structures which form in both the cytoplasm and the nucleus of baculovirus-infected cells.
J Gen Virol 1995 Dec
PMID:Expression and localization of a baculovirus protein phosphatase. 884 98

We have previously shown that in AIDS patients a predominant species of infectious virus can be found which is not neutralized by homologous serum. The presence of the infectious virus was associated with the lack of type-specific antibody directed against the V3 domains of these virions. In contrast to this lack of V3-specific antibody, the other V3 domains of non-infectious virions were well recognized by antibody. To determine whether the lack of a V3-specific antibody response is due to a progressive loss of antibody during human immunodeficiency virus type 1 (HIV-1) infection, we monitored the anti-V3 antibody response in 90 patients over time. Anti-V3 antibodies were monitored by a V3-specific ELISA using 21 different V3 domains as a fusion with glutathione S-transferase (GST-V3) based upon sequences from 11 HIV-1 patient isolates and 10 sequences from an HIV-1 B subtype consensus-like GST-V3 expression library. This strictly heterologous screening showed a loss of V3-specific antibodies in 20 out of the 90 patients tested. To study the in vivo relevance of these findings we analysed V3 antibody loss in two patients. This strictly autologous antibody screening was performed based upon V3 sequences of the patients' cell-free virions. In both patients the loss of a V3-specific antibody could be detected in parallel to a decline of CD4+ T cells. Moreover, the escape of a distinct V3 variant was shown to correlate closely with the loss of the V3-specific antibody.
J Gen Virol 1996 Oct
PMID:Loss of antibody reactivity directed against the V3 domain of certain human immunodeficiency virus type 1 variants during disease progression. 888 71

Grapevine virus B (GVB) is a tentative member of the genus Trichovirus. The 5'-terminal region of the RNA genome of GVB comprises 5437 nucleotides and has been sequenced by the dideoxynucleotide chain termination method. Evidence was obtained that the RNA is capped. Two putative open reading frames (ORFs) were identified. ORF 1 coded for a 194.7 kDa polypeptide with conserved motifs of replication-related proteins of positive-strand RNA viruses (i.e. methyltransferase, helicase and RNA-dependent RNA polymerase, in that order from the N to the C terminus). ORF 2 encoded a 20 kDa polypeptide that did not show any significant sequence homology with protein sequences from the databases. The biological function of this polypeptide was not determined. Although the 20 kDa product was expressed as a fusion protein with glutathione S-transferase in Escherichia coli and an antiserum produced, it could not be identified in GVB-infected plant tissue extracts. The GVB genome had the same size as that of apple chlorotic leaf spot virus (ACLSV), the type species of the genus Trichovirus, but differed substantially in the number (five compared to three), size and order of genes. Differences existed also in the extent of sequence homology between polymerases, which did not cluster together in tentative phylogenetic trees. The results of this study show that definitive and tentative trichovirus species differ molecularly to an extent that may warrant a taxonomic revision of the genus.
J Gen Virol 1996 Oct
PMID:The nucleotide sequence and genomic organization of grapevine virus B. 888 2

The antracyclines induce multiple intracellular effects; however, inhibition of the nuclear enzyme topoisomerase II (TOPO II) is the main mechanism of action. Resistance to anthracyclines in tumor cells is multifactorial. The main mechanisms are: (1) the classic multidrug resistance (MDR) phenotype, which is due to the presence of P-glycoprotein (PGP) in plasma membrane, that is, a "pump" that can extrude a wide range of anticancer drugs. Membrane-active drugs (e.g., verapamil) have been found in vitro to reverse this phenotype. Most clinical studies including chemosensitizers have, however, been disappointing. (2) Non-PGP-mediated MDR: this phenotype is characterized by expression of other proteins in the plasma membrane which are also able to extrude anticancer drugs. (3) Changes in the intracellular distribution of drug: this mechanism has been demonstrated in several cell lines, most often in combination with PGP or non-PGP-mediated resistance. (4) Glutathione transferases (GST) and detoxification mechanisms: these represent a multigene family of enzymes that conjugate glutathione to chemically reactive groups. Direct evidence for a causative role of GST in anthracycline resistance is missing. (5) Alterations in TOPO II (at-MDR): DNA topoisomerases are involved in several aspects of DNA metabolism, in particular genetic recombination, DNA transcription, and chromosome segregation. Low levels of expression or alterations in TOPO II are associated in vitro with resistance. (6) Increased DNA repair: in several cell lines, an increase in the efficacy of DNA repair has been associated with resistance to doxorubicin (DOX). So far, only classic MDR has been shown to contribute to resistance in clinical conditions, whereas evidence for the other mechanisms of resistance is still missing.
Gen Pharmacol 1996 Mar
PMID:Cellular resistance to anthracyclines. 891 38

The D-alanyl-D-alanine-adding enzyme encoded by the murF gene catalyzes the ATP-dependent formation of UDP-N-acetylmuramyl-L-gamma-D-Glu-meso-diaminopimelyl-D-Ala-D-Ala (UDP-MurNAc-tripeptide). MurF has been cloned from Escherichia coli and expressed as a glutathione S-transferase (GST) fusion using the tac promoter-based pGEX-KT vector. From induced, broken cell preparations, highly active fusion was recovered and purified in one step by affinity chromatography. The purified fusion protein was strongly inhibited by substrate UDPMurNAc-tripeptide, a response unaltered by changes in assay pH or by cleavage from the fusion partner. However, this effect was suppressed by the addition of 0.5 M NaCl. Initial velocity and dead-end inhibitor studies with the fusion enzyme were most consistent with a sequential ordered kinetic mechanism for the forward reaction in which ATP binds to free enzyme, followed by tripeptide and D-Ala-D-Ala in sequence prior to product release. Reported homologies between the MurF protein and the three preceding steps of cytoplasmic murein biosynthesis, MurC, -D, and -E, [Ikeda et al. (1990) J. Gen. Appl. Microbiol. 36, 179-187], raise the prospect that all of these enzymes will be found to proceed via this mechanism.
 ...
PMID:Kinetic mechanism of the Escherichia coli UDPMurNAc-tripeptide D-alanyl-D-alanine-adding enzyme: use of a glutathione S-transferase fusion. 897

The nucleotide sequence of the Toscana (TOS) virus M RNA segment contains a single major open reading frame in the viral-complementary sequence, which can encode a polyprotein of 1339 amino acids. To map the TOS M segment product(s), different regions of the putative M polypeptide were expressed as glutathione S-transferase fusion proteins, which were purified and inoculated into mice to produce hyperimmune sera. By Western blot analysis, a protein of approximately 30 kDa and two glycoproteins, G1 and G2, with the same molecular mass (approximately 65 kDa) were identified in TOS virus-infected cells. The 30 kDa protein, which reacted with antibodies raised to the NH2-terminal, was found to be a non-structural protein (designated NSm). By immunoprecipitation analysis of TOS virus-infected cell lysates, both treated or untreated with tunicamycin, the relative positions of glycoproteins G1 and G2 were determined. The gene order, with respect to the genomic M RNA, was found to be 3' NSm-G1 -G2 5'
J Gen Virol 1997 Jan
PMID:Organization of the M genomic segment of Toscana phlebovirus. 901 Feb 88

Papillomavirus DNA replication is primarily dependent upon two viral gene products, E1 and E2. Work with bovine papillomavirus has shown that the E2 protein can bind directly to the E1 protein and enhance the binding of E1 to the viral origin of replication. However, little is known about the mechanism of interaction between E1 and E2 proteins. In this study we have analysed in detail the association between human papillomavirus type 16 (HPV-16) E1 and E2 proteins. Using a purified glutathione S-transferase-HPV-16 E1 fusion protein from Escherichia coli and E2 proteins produced by in vitro transcription-translation, we have developed a rapid and simple method for investigating the association between E1 and E2 in vitro. The binding of E2 to E1 was found to be dependent on sequences in the N-terminal activation domain of the E2 protein. Truncated forms of E2, including a putative repressor form of E2 encoding the DNA binding domain, failed to associate with E1 in this assay. The region of E2 required for efficient binding to E1 was then localized using mutants in the activation domain of E2. These results demonstrated that only a short region of E2 was required for association with E1. This region of E2 was found to be highly conserved amongst all papillomaviruses, suggesting a conservation of E2 function and a common mechanism of interaction between these virally encoded proteins.
J Gen Virol 1995 Apr
PMID:Mutations in the human papillomavirus type 16 E2 protein identify a region of the protein involved in binding to E1 protein. 904 27

The human immunodeficiency virus type 1 Nef protein was expressed in Escherichia coli as a C-terminal fusion with glutathione S-transferase (GST). The ability of GST-Nef to act as a substrate for cellular kinases in vitro was examined by incubation of purified GST-Nef fusion proteins, immobilized on glutathione-agarose beads, with cytoplasmic extracts from a number of human cell lines. In the presence of [gamma32P]ATP, phosphorylation of Nef occurred predominantly on serine residues. Studies with protein kinase inhibitors suggested that protein kinase C (PKC) was involved in Nef phosphorylation. This was supported further by the demonstration that purified PKC was also able to phosphorylate Nef in the absence of cell extract. Serine/threonine phosphorylation of Nef was also observed in vivo when Nef was expressed with a C-terminal GST or 6-histidine tag in Spodoptera frugiperda insect cells by recombinant baculoviruses. In extracts from Jurkat T cells and U937 monocyte/macrophages Nef also associated with a 57 kDa cellular protein that was itself phosphorylated in vitro. Phosphorylation of this Nef-associated protein was inhibited by heparin and is thus likely to be mediated by casein kinase II. The observation that PKC can phosphorylate Nef in vitro raises the possibility that PKC might play a role in regulating both Nef function and the physical interactions between Nef and cellular components.
J Gen Virol 1995 Apr
PMID:The human immunodeficiency virus type 1 Nef protein functions as a protein kinase C substrate in vitro. 904 29

The herpes simplex virus type 1 (HSV-1) capsid protein VP24 (encoded by UL26) was expressed as a GST-fusion protein and used to prepare a group of monoclonal antibodies. These were used to characterize the protein in capsids and virus infected cells and demonstrated that it exists as two polypeptide species. The nature of the relationship between these two species was investigated and found to be associated with disulphide bonding. Under non-reducing conditions a species corresponding to dimers of VP24 was identified in preparations of B capsids, the site of action of the proteinase. Biochemical subcellular fractionation studies suggested that only cleaved forms of UL26 and UL26.5 gene products could be detected in the nucleus of the infected cell at early times post-infection.
J Gen Virol 1997 Mar
PMID:Processing and intracellular localization of the herpes simplex virus type 1 proteinase. 904 21

The E1 and E2 proteins of papillomaviruses are essential for the initiation of viral DNA replication. We have purified the E2 protein of human papillomavirus type 33 (HPV-33) by immunoaffinity chromatography. The purified E2 protein bound with high affinity to all four consensus binding sites of HPV-33 (Kd approximately equal to 2 x 10(-10)M). A putative E2 binding site differing at one position in the second stem of the palindrome was not bound by E2. The E1 protein of HPV-33 purified by affinity chromatography using glutathione S-transferase as tag displayed specific DNA-binding activity in footprint analyses protecting HPV-33 nucleotides 7896 to 7909/1 to 18 from DNasel digestion. Hypersensitive sites at position 6 on the sense and position 1 on the antisense strand were observed in the middle of the protected region. An E1/E2 complex protected the E1 binding site and E2 binding sites from DNasel digestion suggesting that both proteins retain DNA-binding activity in the complex.
J Gen Virol 1997 Apr
PMID:Characterization of the DNA-binding activity of the E1 and E2 proteins and the E1/E2 complex of human papillomavirus type 33. 912 65


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>