Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

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 identified a human cDNA that is homologous to the chicken kinectin, a putative receptor for the organelle motor kinesin. The human cDNA clone hybridized to a single 4.6-kb mRNA species that codes for a protein of 156 kDa molecular mass. The predicted primary translation product contains an N-terminal transmembrane helix followed by a bipartite nuclear localization sequence and two further C-terminal leucine zipper motifs. In addition, the aminoacid sequence revealed a large region (327-1362) of predicted alpha-helical coiled coils. A monoclonal antibody CT-1 raised against a GST-kinectin fusion protein produced a perinuclear, endoplasmic reticulum-like staining pattern in diverse cell types from different species, indicating evolutionary conservation. Monoclonal antibody CT-1 and anti-chicken kinectin antibodies cross-reacted both in Western blotting and immunoprecipitation with a 160-kDa protein, confirming the antigenic identity of this 160-kDa protein with chicken kinectin. Epitope tagging studies revealed that the nuclear localization sequence motif of kinectin is not functional. Furthermore, a truncated kinesin cDNA lacking the N-terminal hydrophobic domain revealed a nonspecific cytoplasmic staining pattern. Together the data suggest that kinectin is an integral membrane protein anchored in the endoplasmic reticulum via a transmembrane domain.
...
PMID:Molecular cloning and characterization of human kinectin. 778 43

Calnexin is a 90-kDa integral membrane protein of the endoplasmic reticulum (ER). Calnexin binds Ca2+ and may function as a chaperone in the transition of proteins from the ER to the outer cellular membrane. We have purified human calnexin in association with the human interferon-gamma receptor and cloned calnexin cDNA from placenta. Fragments of calnexin have been prepared as glutathione S-transferase fusion proteins and analyzed for their abilities to bind 45Ca2+ and ruthenium red. A subdomain containing four internal repeats binds Ca2+ with the highest affinity. This sequence is highly conserved when compared to calreticulin (a luminal ER protein), an Onchocerca surface antigen, and yeast and plant calnexin homologues. Consequently, this sequence represents a conserved motif for the high-affinity binding of Ca2+, which is clearly distinct from the "E-F hand" motif. An adjacent subdomain, also highly conserved and containing four internal repeats, fails to bind Ca2+. The carboxyl-terminal, cytosolic domain is highly charged and binds Ca2+ with moderate affinity, presumably by electrostatic interactions. The calnexin amino-terminal domain (residues 1-253) also binds Ca2+, in contrast to the amino-terminal domain of calreticulin, which is relatively less acidic. We have also determined the cDNA sequences of mouse and rat calnexins. Comparison of the known mammalian calnexin sequences reveals very high conservation of sequence identity (93-98%), suggesting that calnexin performs important cellular functions. The gene for human calnexin is located on the distal end of the long arm of human chromosome 5, at 5q35.
...
PMID:Human, mouse, and rat calnexin cDNA cloning: identification of potential calcium binding motifs and gene localization to human chromosome 5. 813 57

Using the percoll density gradient method for rapid isolation of organelles the distribution of glutathione system enzymes in the rat brain was characterized including glutathione S-transferase (GST), glutathione peroxidase (GPx), and glutathione reductase (GR). In the fraction of mitochondria, the shares of GPx, GR, and GST were found to be as much as 92, 61, and 15% from their respective general activities. No enzymatic activity was found in lysosomes. Fractions of organelles with low density (microsomes, Golgi complex, cytoplasmic membranes) were cross-contaminated. Nevertheless, on the base of the established dynamics of distribution of the marker enzyme activity among various cell organelles it is suggested that, besides mitochondria, the glutathione system enzymes may be localized primarily in the endoplasmic reticulum, rather than in other organelles.
...
PMID:[The subcellular distribution of the glutathione system enzymes in the brain tissue of the rat]. 826 64

Malignant tumor cells can escape CD8+ cytotoxic T cell killing by downregulating class I major histocompatibility complex (MHC) expression. Stable class I MHC surface expression requires loading of the heavy chain/light chain dimer with antigenic peptide, which is delivered to class I MHC molecules in the endoplasmic reticulum by the presumed peptide transporter, encoded by the transporter associated with antigen presentation (TAP) 1 and 2 genes. We have investigated whether loss of class I MHC expression frequently observed in different cancers could result from interference with TAP function. A polyclonal antiserum, raised against a bacterial glutathione S-transferase/human TAP-1 fusion protein, was used for the immunohistochemical analysis of TAP-1 expression in 76 cervical carcinomas. Results showed loss of TAP-1 expression in neoplastic cells in 37 out of 76 carcinomas. Immunohistochemical double staining procedures in combination with HLA-specific antibodies revealed congruent loss at the single cell level of TAP-1 and HLA-A/B expression in 28 out of 37 carcinomas. The remaining samples expressed HLA(-A) in the absence of TAP-1 (n = 6) or showed loss of HLA(-A/B) while TAP-1 was expressed (n = 3). These data strongly indicate that inhibition of peptide transport by downregulation of TAP-1 is a potential strategy of malignant cells to evade immune surveillance.
...
PMID:Loss of transporter protein, encoded by the TAP-1 gene, is highly correlated with loss of HLA expression in cervical carcinomas. 827 Aug 78

The present study is aimed to elucidate the changes in glutathione S-transferase (GST) activity and GST subunit components in primary cultured rat hepatocytes. Enzyme activity was measured with 1-chloro-2,4-dinitrobenzene as cosubstrate. The activity decreased at 48 hr, and subsequently increased and returned to levels initially observed at 12 hr by 120 hr. Phenobarbital caused an induction of GST activity in culture at 72 and 168 hr. Immunocytochemical studies were performed using a peroxidase-anti-peroxidase technique with three polyclonal antibodies: anti-Ya, Yb1 and Yp. With anti-Ya, hepatocytes were persistently positive up to 144 hr in cell culture. With anti-Yb1, hepatocytes were positive at 24 hr, though positivity then gradually decreased. On the other hand, with anti-Yp, cells were almost negative at 48 hr and became obviously positive at 96 hr. Immunoelectron microscopy with anti-Yb1 using the avidin-biotin ferritin method revealed ferritin particles in the ribosomes on endoplasmic reticulum as well as in the free cytoplasmic space. In conclusion, the GST subunit components are in a state of dynamic change in cultured rat hepatocytes, and overall time-dependent increase in the total activity of the enzyme can be accounted for by increased expression of the Yp subunit. Finally, the intracellular localization of Yb1 subunit was clarified in the present report.
...
PMID:Glutathione S-transferases in primary cultured rat hepatocytes. 844 Apr 22

Hsp47, an endoplasmic reticulum-resident heat shock protein in fibroblasts, has gelatin-binding properties. It had been hypothesized that it functions as a chaperone regulating procollagen chain folding and/or assembly, but the mechanism of the hsp47-procollagen I interaction was not clear. Hsp47 could bind to both denatured and native procollagen I. A series of competition studies were carried out in which various collagens and collagen domain peptides were incubated with 35[S]-methionine-labeled murine 3T6 cell lysates prior to mixing with gelatin-Sepharose 4B beads. The gelatin-bound proteins were collected and analyzed by gel electrophoresis and autoradiography. Collagenase digested procollagen I had the same effect as denatured intact procollagen, indicating that the propeptides were the major interaction sites. The addition of intact pro alpha 1(I)-N-propeptide at 25 micrograms/ml completely inhibited hsp47 binding to the gelatin-Sepharose. Even the pentapeptide VPTDE, residues 86-90 of the pro alpha 1(I)-N-propeptide, inhibits hsp47-gelatin binding. These data implicating the pro alpha 1(I)-N-propeptide domain were confirmed by examination of polysome-associated pro alpha chains. The nascent pro alpha 1(I)-chains with intact N-propeptide regions could be precipitated by monoclonal hsp47 antibody 11D10, but could not be precipitated by monoclonal anti-pro alpha 1 (I)-N-propeptide antibody SP1.D8 unless dissociated from the hsp47. GST-fusion protein constructs of residues 23-108 (NP1), 23-151 (NP2), and 23-178 (NP3) within the pro alpha 1 (I)- N-propeptide were coupled to Sepharose 4B and used as affinity beads for collection of hsp47 from 3T6 cell lysates. NP1 and NP2 both showed strong specific binding for lysate hsp47. Finally, the interaction was studied in membrane-free in vitro cotranslation systems in which the complete pro alpha 1(I)- and pro alpha 2(I)-chain RNAs were translated alone and in mixtures with each other and with hsp47 RNA. There was no interaction evident between pro alpha 2(I)-chains and hsp47, whereas there was strong interaction between pro alpha 1(I)-chains and nascent hsp47. SP1.D8 could not precipitate pro alpha 1(I)-chains from the translation mix if nascent hsp47 was present. These data all suggest that if hsp47 has a "chaperone" role during procollagen chain processing and folding it performs this specific role via its preferential interaction with the pro alpha 1 (I) chain, and the pro alpha 1(I) amino-propeptide region in particular.
...
PMID:Endoplasmic reticulum protein Hsp47 binds specifically to the N-terminal globular domain of the amino-propeptide of the procollagen I alpha 1 (I)-chain. 856 53

A yeast mutant (LT06) was isolated that showed no growth on iron-limited medium but normal growth on iron-replete medium. A gene cloned from a genomic yeast library complemented the defect, allowing growth on low iron medium. Allelic segregation analysis demonstrated that the cloned gene was the normal allele rather than a high copy suppressor. A disruption mutant was nonviable, indicating that the gene was essential. Sequence analysis and functional assays indicated that the cloned gene was identical to ERG25, a gene that codes for methyl sterol oxidase. Incubation of LT06 in low iron medium resulted in marked changes in lipid metabolism, including the accumulation of fatty acids, triglycerides, methyl sterols, and other sterol precursors. A human homologue of ERG25 was cloned, sequenced, and mapped to human chromosome 4q32-34. Analysis of the data base with both ERG25 and the human homologue resulted in the identification of a putative set of metal binding motifs with similarity to that seen in a family of membrane desaturases-hydroxylases. Western analysis using antibodies to an Erg25-GST fusion protein detected two proteins of 34 and 75 kDa. Both proteins are membrane bound and contain one N-glycosyl unit. Immunofluorescence data suggest that the proteins are present in the endoplasmic reticulum and plasma membrane. Although ERG25 transcripts are not iron regulated, there is a large increase in the concentration of transcript in the mutant LT06 grown in low iron medium. These results suggest that the enzyme is regulated not by iron but by an end product of the ergosterol pathway.
...
PMID:Characterization of yeast methyl sterol oxidase (ERG25) and identification of a human homologue. 866 58

Ultrastructural, stereological and biochemical alterations in isolated hepatocytes and the permanent fibrocyte-like cell line R1 from rainbow trout (Oncorhynchus mykiss) exposed to 0, 0.2, 2 and 20 mg/l of the phosphorodithioate pesticide disulfoton (Solvirex, O,O-diethyl S-2-ethylthioethyl phosphorodithioate) for up to 5 days were investigated. In both R1 cells and isolated hepatocytes, distinct dose- and time-dependent morphological alterations including diminished amounts of heterochromatin, proliferation of lysosomal elements, dilation and vesiculation of endoplasmic reticulum cisternae, induction of concentric membrane whorls and an increased amount of lipid droplets could be detected at concentrations of > or = 2 mg/l (R1 cells) and > or = 0.2 mg/l disulfoton (hepatocytes). Additional effects in isolated hepatocytes comprised marginalization of heterochromatin, myelin-like structures attached to mitochondrial membranes, formation of ring-shaped mitochondria, proliferation of smooth endoplasmic reticulum, reduction of rough endoplasmic reticulum, induction of ring-shaped Golgi cisternae, glycogen depletion and occurrence of glycogenosomes. Structural changes in isolated hepatocytes could be correlated to suppression of lactate dehydrogenase, glucose-6-phosphate dehydrogenase, alanine aminotransferase, malic enzyme, esterase as well as glutathione S-transferase, but to a stimulation of 7-ethoxycoumarin-O-deethylase and the rate of lipid peroxidation at concentrations > or = 0.01 mg/l disulfoton. Comparison with data from in vivo experiments with rainbow trout indicate the suitability of in vitro techniques for the evaluation of the toxicological potential of a wide range of ecotoxicologically relevant substances.
...
PMID:Cytological and biochemical response of R1 cells and isolated hepatocytes from rainbow trout (Oncorhynchus mykiss) to subacute in vitro exposure to disulfoton. 891 71

Interleukin-3 (IL-3) is a hematopoietic growth factor receptor which stimulates the proliferation of multilineage progenitor cells. It is known that IL-3 stimulates tyrosine phosphorylation while transducing a mitogenic signal. The signal transduction pathways activated by the IL-3 receptor, however, are not fully understood. In this study a protein tyrosine phosphatase has been over-expressed in the IL-3 dependent, murine myeloid progenitor cell line, 32D cl3 in order to test whether altering the levels of tyrosine phosphorylation would change IL-3 stimulated proliferation. These cells were transfected with a metal-inducible expression vector containing a rat cDNA encoding PTP1. A low basal level of rat PTP1 message and protein was detected in cells transfected with the PTP1 vector, and zinc treatment resulted in a three- to fourfold increase in the amount of PTP1 message, protein and catalytic activity. Over-expression of PTP1 resulted in a two- to threefold decrease in IL-3 stimulated proliferation. Cells over-expressing PTP1 also exhibited decreased levels of tyrosine phosphorylation; phosphorylation of the IL-3 receptor beta subunit and the Shc protein were both dramatically decreased. Thus, PTP1 over-expression negatively modulated IL-3 signal transduction. To identify potential substrates of PTP1, 32D cl3 cells were transfected with a catalytically inactive PTP1 mutant, PTP1(C/S). Three tyrosine-phosphorylated proteins of MW 140, 79 and 69 k coprecipitated with PTP1(C/S). We believe that the 140 kDa protein represents the beta subunit of the IL-3 receptor. In addition, a GST-fusion protein containing active PTP1 dephosphorylated the beta-subunit in an in vitro assay. By immunofluorescent microscopy over-expressed PTP1(C/S) co-localized largely with calnexin, an endoplasmic reticulum-associated protein. Immunofluorescent microscopy also indicated that PTP1(C/S) and the beta subunit co-localized at discrete sites at the plasma membrane and around a cytoplasmic organelle where most of the beta subunit was located. These observations suggest PTP1 over-expression may down-regulate the growth response to IL-3 through dephosphorylation of the IL-3 receptor, perhaps in an intracellular compartment, thereby inhibiting propagation of the IL-3 mitogenic signal.
...
PMID:Over-expression of protein tyrosine phosphatase 1 (PTP1) alters IL-3-dependent growth and tyrosine phosphorylation. 895 78

The systemic toxicity of tris(4-chlorophenyl)methanol (TCPM) was studied in male and female rats following 4 weeks dietary exposure dosed at 1, 10 and 100 ppm. An increased spleen to body weight ratio was observed in males at 10 and 100 ppm and in females at 100 ppm. An increased liver to body weight ratio was detected in both sexes at 100 ppm. Dose-related increases in hepatic Phase-I (AH, APDM, EROD and PROD) and Phase-II (UDPGT, GST) enzyme activities were observed generally at 10 and 100 ppm, with the elevation in PROD activity being the most marked. Increased urinary ascorbic acid was detected in both males and females after 1 week of treatment at 100 ppm and after 4 weeks of treatment at 10 and 100 ppm. At 10 and 100 ppm, elevated % lymphocytes were found in males, and higher white blood cell and lymphocyte counts were observed in females. In the liver, mild to moderate cytoplasmic changes consistent with proliferation of smooth endoplasmic reticulum were present in rats of both sexes at 10 and 100 ppm, and increased number of hepatocytes undergoing apoptosis were observed in male rats at 100 ppm. Mild splenic changes consisting of sinus hyperplasia in males and females at 100 ppm and mantle zone atrophy in males at 100 ppm were also observed. It was concluded that TCPM at a dietary concentration of 10 ppm (equivalent to 1.2 mg/kg/day) produced systemic changes in rats that included various hepatic effects, increased splenic weight, and modulations in white blood cells and lymphocyte counts.
...
PMID:Effects of tris(4-chlorophenyl)methanol on the rat following short-term oral exposure. 901 Oct 26


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

---