7-Glutamyltransferase

Taracha E, Habrat BS, Wozniak P, Walkowiak J and Szukalski B (2001). The activity of (3-hexosaminidase (uHex) and y-glutamyltransferase (uGGT) in urine as non invasive markers of alcohol abuse I. Alcohol-dependent subjects. World Journal of Biological Psychiatry, 2, 184-189. 

Hatzinger, P.B. and Stevens, J.L. (1989). Rat kidney proximal tubule cells in defined medium the roles of cholera toxin, extracellular calcium and serum in cell growth and expression of y-glutamyltransferase. In Vitro Cell. Dev. Biol. 25(2) 205-212. 

Protein-glutamine y-glutamyltransferase [Caj— fibrin-stabilizing factor ... 

This enzyme [EC 2.3.2.13], also known as protein glutamine y-glutamyltransferase, catalyzes the calcium ion-dependent reaction of the side chain of a glutamyl residue in a protein with an alkylamine to generate an A -alkylglutaminyl residue in the protein and ammonia. 

AFFINITY LABELING AGARITINE y-GLUTAMYLTRANSFERASE y-GLUTAMYLTRANSPEPTIDASE Aggregation,... 

Serum ALP and total bilirubin (unconjugated and conjugated fractions) are traditionally used to monitor cholestatic injury. The ALP families of enzymes are zinc metalloproteases that are present in nearly all tissues. In the liver, ALP is immu-nolocalized to the microvili of the bile canaliculus [124]. Increased synthesis of ALP and its release into the circulation occurs within hours of cholestatic injury [129]. Serum assays of 5 -nucleotidase (5 -NT) or y-glutamyltransferase activity (GGT) are used to confirm the liver as the specific origin for the elevation of ALP. Increases in serum bilirubin or bile acids are usually the result of bile retention subsequent to impaired bile flow, increased production associated with accelerated erythrocyte destruction, or altered bilirubin metabolism [129]. 

CA030 Nakanishi, N., K. Nakamura, K. Nakajima, K. Suzuki, and K. Tatara. Coffee consumption and decreased serum gamma-glutamyltransferase a study of middle-aged Japanese men. EurJ Epidemiol 2000 16(5) 419-423. 

Honjo, S., S. Kono, M. P. Coleman, et al. Coffee drinking and serum gamma-glutamyltransferase an extended study CA064 of Self-Defence Officials of Japan. Ann Epidemiol 1999 9(5) 325-331. 

Transient, mild increases in liver enzyme levels, up to three times the upper limit of normal, do not necessitate discontinuation of valproate. Although y-glutamyltransferase levels are often checked by clinicians, these levels are often increased, without clinical significance, in patients receiving valproate and carbamazepine (Dean and Penry 1992). Likewise, plasma ammonia levels are often increased transiently during valproate treatment, but this finding does not necessitate interruption of treatment (Jaeken et al. 1980). Increases in transaminase levels are often dose dependent. If no... 

After the conjugation reaction, the first catabolic step, removal of the glutamyl residue, is catalyzed by the enzyme y-glutamyltranspeptidase (glutamyltransferase). 

Figure 7.29 The metabolic activation of hexachlorobutadiene. The glutathione conjugate is degraded to a cysteine conjugate in two stages involving the action of (1) y-glutamyltransferase and (2) cysteinyl glycinase.

An alternative fate for the GSH conjugate is transportation via the blood to the kidney, filtration out of the blood and in the brush border of the tubular cells glutamyltransferase, and cleavage of the conjugate by a dipeptidase to yield the cysteine conjugate. The cysteine conjugate is then taken up by the amino acid transporter system into the proximal tubular cell where toxicity occurs. The result of this is then basically the same as the other scenario. 

Thus, the nephrotoxicity and covalent binding of metabolites to renal protein can be reduced by treating animals with the organic acid probenecid, which competes with the cysteine conjugate for the active uptake system. The cytotoxicity of the GSH conjugate of HCBD in vitro is reduced by inhibitors of (3-glutamyltransferase and (3-lyase, indicating that both these enzymes are essential for the toxicity. 

If the (3-lyase enzyme, or the renal basolateral membrane transport system, or y-glutamyltransferase, or cysteinylglycinase is inhibited, the nephrotoxicity of DCVC can be reduced, indicating that each of these processes is involved. 

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