Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An apparently specific glutathione oxidase activity is present in renal cortex, epididymal caput, jejunal villus tip cells, choroid plexus, and retina (but not in liver). The activity is membrane-bound and is localized on the luminal surface of the brush border membranes of the kidney and jejunum. The distribution and localization of the oxidase are similar to those of gamma-glutamyl transpeptidase, suggesting that there is a significant relationship among the translocation of intracellular glutathione, the extracellular oxidation of glutathione to glutathione disulfide, and the reactions of the gamma-glutamyl cycle. Thus, both glutathione present in the blood plasma and intracellular glutathione translocated to the cell surface are accessible to oxidation and transpeptidation. Acceptor substrates of the transpeptidase (e.g., L amino acids) promote transpeptidation and decrease oxidation of glutathione. Conversion of glutathione to glutathione disulfide is followed by utilization of the latter compound by gamma-glutamyl transpeptidase and dipeptidase. Although intracellular oxidation of glutathione to glutathione disulfide is readily reversed by the action of glutathione reductase, glutathione disulfide formed extracellularly cannot be reduced; instead, it undergoes hydrolytic and transpeptidation reactions leading to gamma-glutamyl amino acid and amino acid products which may be recovered by being transported into the cell.
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PMID:Conversion of glutathione to glutathione disulfide by cell membrane-bound oxidase activity. 3 3

The effect of voluntary exercise on 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB)-induced hepatomas was investigated in male Jc1:Wistar rats. Beginning at 10 weeks of age, animals were divided into two groups (sedentary and exercise) and housed in individual cages. Food intake and wheel exercise were automatically controlled in the cages of the exercise group. Body weights were monitored throughout the study. Food availability was controlled in order to equate length and weight gain. From 27 weeks to termination of the study at 62 weeks, all animals were administered 3'-Me-DAB in the diet at a dose level of 0.0177 g/day/kg body wt. All animals were sacrificed at 62 weeks of age. The incidence of hepatomas was significantly lower in the exercise group as compared with the sedentary group (0% and 65%, respectively). Liver weight was significantly greater in the exercise group compared with sedentary animals without hepatomas. The weight of epididymal fat pads was significantly lower in the exercise group. Serum alkaline phosphate was significantly higher in the exercise group as compared with the sedentary group. Serum gamma-glutamyl-transpeptidase levels were higher in the sedentary group than in the exercise group. In addition, gamma-glutamyl-transpeptidase levels were significantly higher in sedentary animals with hepatomas than in sedentary animals without hepatomas. These results demonstrate that voluntary exercise decreases 3'-Me-DAB-induced hepatomas and that this decrease is associated with an increase in serum alkaline phosphatase and a decrease in serum gamma-glutamyl-transpeptidase levels.
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PMID:Effect of voluntary exercise on 3'-methyl-4-dimethylaminoazobenzene-induced hepatomas in male Jc1:Wistar rats. 810 85

1. gamma-Glutamyl-transpeptidase (gamma-GTP), present at low levels in the testis, seminal vesicle, prostate gland and epididymis in rat at 4 days of age, showed rapid developmental increases at the time of weaning. 2. Administration of nonylphenols (NP) to the neonatal male rat pup (from days 1 to 15) impaired the subsequent development of gamma-GTP in the epididymis but not in the testis, seminal vesicles or prostate gland. 3. Single injection of NP to weaned pups at approximately 22 days of age decreased gamma-GTP in the epididymis but not in other male accessory sex organs. This effect was transient, dose-dependent and blocked by the oestrogen receptor-specific antagonist ICI 182,780. 4. Single injection of oestradiol to weaned rat at approximately 22 days of age also decreased gamma-GTP in the epididymis but not in the testis, prostate gland or seminal vesicles. 5. In in vitro assays, NP did not inhibit epididymal gamma-GTP activity even at 100 microM final concentration. Under similar conditions, acivicin, a specific inhibitor for gamma-GTP, showed a dose-dependent inhibition of gamma-GTP activity. 6. It is suggested that NP impair gamma-GTP expression in the epididymis of developing male rat and act in part via the oestrogen receptor.
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PMID:Modulation of rat epididymal gamma-glutamyl transpeptidase by nonylphenols. 1103 10

Sperm thiol oxidation during sperm maturation is important for sperm component stabilization, the acquisition of sperm motility, and fertilizing ability. A correct degree of oxidation is required, since spermatozoa are very susceptible to oxidative damage. The pathways involved in physiologic sperm thiol oxidation in the epididymis are not completely understood. The nonprotein thiol glutathione (GSH), in addition to playing a major role as an antioxidant and in eliminating toxic compounds, has been implicated in prooxidation processes in various cells, via gamma-glutamyl-transpeptidase (gamma-GT)-dependent catabolism. Little information is available on the dynamics of nonprotein thiols (NPSHs) and disulfides (NPSSNPs) in spermatozoa and epididymal fluid (EF) during sperm passage in the epididymis. It is not clear whether NPSHs and NPSSNPs are involved in sperm protein thiol (PSH) oxidation or whether GSH catabolism in the epididymis can serve as a pathway for sperm PSH oxidation. In the present study, we used the thiol fluorescence labeling agent monobromobimane to analyze NPSHs and nonprotein disulfides (NPSSRs) (R, nonprotein or protein) in spermatozoa and EF in the rat caput and cauda epididymis. NPSH levels are shown to be significantly higher in the caput than in the cauda (spermatozoa and fluid). GSH in the caput lumen is subject to high gamma-GT activity. A marked loss of sperm GSH and a shift to an oxidized state (resulting in a significantly higher concentration of glutathione disulfides [GSSRs] than GSH) occur during the passage of spermatozoa from the caput to the cauda epididymis. Caput EF and extracellular NPSSNPs induce sperm thiol oxidation. The results suggest that epididymal NPSH/NPSSNP participates in sperm PSH oxidation and that some reactions of GSH in the gamma-GT pathway (in the epididymis) provide oxidizing power, leading to physiologic sperm thiol oxidation.
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PMID:Nonprotein thiols and disulfides in rat epididymal spermatozoa and epididymal fluid: role of gamma-glutamyl-transpeptidase in sperm maturation. 1608 41