Disease relevance of GGT1

• Notably, gamma-glutamyl transpeptidase isolated from Escherichia coli, which exhibits about 80% amino acid sequence homology with the rat enzyme, has only about 0.1% of its specific enzymatic activity and is not glycosylated [1].
• Long-term administration of pentoxifylline (16 mg/kg orally, 5 days/wk for 12 wk) in an animal model of liver fibrosis prevented elevations in gamma-glutamyl transpeptidase and alkaline phosphatase levels and prevented the reduction in serum albumin level normally observed in this animal model of liver disease [2].
• L-azaserine toxicity in established cell lines: correlation with gamma-glutamyl transpeptidase activity [3].
• To determine the role of leukotriene (LT)-degrading enzymes in allergic reactions, we studied the effects of inhibitors of gamma-glutamyl transpeptidase (gamma-GTP) and dipeptidases on increases in pulmonary insufflation pressure (PIP) and vascular permeability induced by ovalbumin (OA) antigen in guinea pigs sensitized to OA antigen in vivo [4].
• Of these biochemical parameters, only gamma glutamyl transpeptidase was significantly elevated in test animals with experimental autoimmune uveitis [5].

High impact information on GGT1

• Acivicin is a potent inhibitor of gamma-glutamyl transpeptidase (EC 2.3.2.2), an enzyme of importance in glutathione metabolism [6].
• gamma-Glutamyl transpeptidase is associated with the membranes of a number of epithelial and lymphoid cells [7].
• gamma-Glutamyl transpeptidase, a highly glycosylated heterodimeric enzyme that is usually attached to the external surface of cell membranes, is of major importance in the metabolism of glutathione [1].
• The serine residue required for catalysis of gamma-glutamyl transpeptidase was identified by site-specific mutagenesis of the conserved serine residues on the basis of sequence alignment of the light subunit of human, rat, pig and two bacterial enzymes [8].
• S-(1,2-Dichlorovinyl)-L-glutathione is not toxic when the cells are pretreated with AT-125, an inhibitor of gamma-glutamyl transpeptidase [9].

Chemical compound and disease context of GGT1

• Administration of ascorbic acid also reduced the activity of gamma-glutamyl transpeptidase (GGT), the marker enzyme of alcohol induced toxicity [10].
• Alamar Blue reduction, gamma-glutamyl transpeptidase activity (GGT), lactate dehydrogenase activity (LDH) and remnant protein were used to assay cell toxicity [11].

Biological context of GGT1

• Alignment of the porcine and the published rat gamma-glutamyl transpeptidase cDNA sequences revealed an average identity of 79%, except for a small region of 194 base pairs containing a high number of mismatches [12].
• Kinetics of the conversion of leukotriene C by gamma-glutamyl transpeptidase [13].
• The presence of gamma-glutamyl transpeptidase (GGT) in boar spermatozoa and the potential role of the GGT at sperm penetration were examined using in vitro matured porcine oocytes [14].
• Chloride, creatinine, glucose, total protein, sodium, and BUN concentrations, alanine transaminase and gamma glutamyl transpeptidase activities, RBC count, mean corpuscular volume, and Hct did not significantly differ between IO and venous samples [15].
• To investigate this possible regulatory mechanism, we compared growth behavior, morphology, and appearance of two differentiated functions, Na-hexose symport (SYMP) and gamma-glutamyl transpeptidase (gamma-GT), in the LLC-PK1 line and two PKA-deficient mutants (FIB4 and FIB6) [16].

Anatomical context of GGT1

• In order to understand the mechanisms regulating the blood-brain barrier we isolated a cDNA clone for gamma-glutamyl transpeptidase from purified porcine brain capillaries by cross-species DNA hybridization using a DNA fragment from a rat kidney cDNA clone [12].
• Cloning and expression of gamma-glutamyl transpeptidase from isolated porcine brain capillaries [12].
• The 2.2-kb transcript of brain gamma-glutamyl transpeptidase is mainly expressed in the endothelial cells of brain microvessels, in agreement with previous data that showed the brain protein being localized within the blood-brain barrier [12].
• Confluent monolayers of LLC-PK1 cells, an epithelial cell derived from a normal pig kidney, contain high levels of alkaline phosphatase and gamma-glutamyl transpeptidase activities [17].
• Alkaline phosphatase and gamma-glutamyl transpeptidase as polarization markers during the organization of LLC-PK1 cells into an epithelial membrane [17].

Associations of GGT1 with chemical compounds

• The accumulated product during the transport of glutamate in the gamma-glutamyl transpeptidase reconstituted system containing intravesicular glutathione was identified as gamma-glutamyl-glutamate [18].
• The uptake of glutamate in the reconstituted system was sensitive to the temperature of incubation and to the inhibitors (serine-borate, azaserine, and 6-diazo-5-oxo-L-norleucine) of gamma-glutamyl transpeptidase activity [18].
• The conversion of leukotriene D3 to leukotriene C3 was catalyzed by gamma-glutamyl transpeptidase which performed a reverse reaction due to the high tissue concentrations of glutathione [19].
• Corresponding cysteinylglycine compounds (leukotriene D3 and 11-trans leukotriene D3) were obtained from the leukotriene C3 isomers by treatment with kidney gamma-glutamyl transpeptidase [20].
• The binding of LTC4 to guinea pig lung and rat lung exhibited similar characteristics, but the former was observed only in the presence of the gamma-glutamyl transpeptidase inhibitor, serineborate complex [21].

Other interactions of GGT1

• The isolates were gram-negative, spiral bacteria which grew under microaerophilic conditions at 37 degrees C, but not at 25 or 42 degrees C, and produced urease, catalase, oxidase, alkaline phosphatase, and gamma-glutamyl transpeptidase [22].
• In contrast, the activity of the GSH degradation enzyme, gamma-glutamyl transpeptidase, was suppressed by GH administration in heart and liver [23].
• Maltase, sucrase, lactase and gamma-glutamyl transpeptidase (gamma-GT) activities were analyzed in jejunal mucosa [24].
• Significant increases in serum aspartate amino transferase, gamma glutamyl transpeptidase, lactate dehydrogenase, bilirubin, and cholesterol occurred from d 10 through 31 [25].
• Elevated activity of gamma-glutamyl transpeptidase in the kidneys of pregnant animals, and aspartate aminotransferase in the liver of nonpregnant guinea pigs were observed [26].

Analytical, diagnostic and therapeutic context of GGT1

• Tissue-specific expression and diversity of the gamma-glutamyl transpeptidase mRNA transcripts in various porcine and human tissues were analysed by Northern blot hybridization [12].
• High performance liquid chromatography analyses indicated that, in the presence of the gamma-glutamyl transpeptidase inhibitor L-serine-borate (80 mM), less than 2% of membrane-bound [3H]LTC4 was converted at 20 degrees to [3H]leukotriene D4 or [3H]leukotriene E4 [27].
• Intraluminal glutathione breakdown and its constituent amino acid uptake were suppressed with the irreversible inhibitor of gamma-glutamyl transpeptidase acivicin; ammonia production was present and incremented with declines in perfusion pH [28].
• Ethanol added to the cell culture at a time when low constant activity is reached, reactivates the gamma-glutamyl transpeptidase to 30% of the initial value [29].

References