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

1. Pyruvate dehydrogenase phosphate phosphatase activity in rat epididymal fat-pads was measured by using pig heart pyruvate dehydrogenase [32P]phosphate. About 80% was found to be extramitochondrial and therefore probably not directly concerned with the regulation of pyruvate dehydrogenase activity. The extramitochondrial activity was sensitive to activation by Ca2+, but perhaps less sensitive than the mitochondrial activity.
 ...
PMID:Regulation of pyruvate dehydrogenase and pyruvate dehydrogenase phosphate phosphatase activity in rat epididymal fat-pads. Effects of starvation, alloxan-diabetes and high-fat diet. 0 18

Adipose tissue and liver from vitamin B6-deficient rats have an increased lipogenic capacity. Whether this phenomenon is accompanied by changes in the activities of certain enzymes involved in the metabolism of carbohydrate and lipid, or by altered transport of glucose into adipocytes, has been studied. Five glycolytic enzymes (hexokinase, phosphoglucose isomerase, phosphofructokinase, aldolase, and pyruvate kinase), two pentose phosphate pathway enzymes (glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase), malic enzyme, and ATP citrate lyase were measured in the epididymal adipose tissue, livers and kidneys of vitamin B6-deficient and control rats. Vitamin B6 deficiency did not significantly affect the glycolytic enzyme levels in the tissues studied, or the dehydrogenases measured in adipose tissue and kidneys. Liver glucose-6-phosphate dehydrogenase, and adipose tissue and liver malic enzyme were significantly lowered in deficient rats compared to ad libitum and pair-fed controls. Adipose tissue and liver ATP citrate lyase activities were also significantly decreased by vitamin B6 deficiency. In the presence of insulin, the uptake of glucose and 3-O-methyl glucose, a non-metabolizable sugar, by fat pads from deficient rats was greater than uptake by fat pads from control rats. These observations suggest that the increased glucose utilization by adipose tissue and liver of vitamin B6-deficient rats is not directly related to changes in the enzymes studied, but in the case of adipose tissue, may be explained, at least in part, by enhanced glucose uptake.
 ...
PMID:Effects of vitamin B6 deficiency on liver, kidney, and adipose tissue enzymes associated with carbohydrate and lipid metabolism, and on glucose uptake by rat epididymal adipose tissue. 13 63

1. The mechanism by which insulin activates pyruvate dehydrogenase in rat epididymal adipose tissue was further investigated. 2. When crude extracts, prepared from tissue segments previously exposed to insulin (2m-i.u/ml) for 2min, were supplemented with Mg-2+, Ca-2+, glucose and hexokinase and incubated at 30 degrees C, they displayed an enhanced rate of increase in pyruvate dehydrogenase activity compared with control extracts. 3. When similar extracts were instead supplemented with fluoride, ADP, creatine phosphate and creatine kinase, the rate of decrease in pyruvate dehydrogenase activity observed during incubation at 30 degrees C was unaffected by insulin treatment. 4. It is suggested that insulin increases the fraction of pyruvate dehydrogenase present in the tissue in the active dephospho form by increasing the activity of pyruvate dehydrogenase phosphate phosphatase.
 ...
PMID:Activation of pyruvate dehydrogenase in adipose tissue by insulin. Evidence for an effect of insulin on pyruvate dehydrogenase phosphate phosphatase. 16 82

The reversible deactivation of chicken adipose tissue hormone-sensitive lipase alpha(previously activated with Mg2+ ATP and adenosine 3':5'-monophosphate) required Mg2+ and was inhibited by phosphate. These results are consistent with the assumption that deactivation of the protein kinase-activated enzyme is catalyzed by a lipase phosphatase. Cholesterol ester is catalyzed by a lipase phosphatase. Cholesterol ester hydrolase similarly was activated and reversibly deactivated. The activity of endogenous lipase phosphatase in pH 5.2 precipitate fractions was reduced, and in some cases eliminated, by incubation at 50 degrees for 20 min in buffer containing 20% glycerol. Heating at 50 degrees greatly increased the apparent percentage activation of triglyceride and cholesterol ester hydrolases but this was due to a selective decrease in basal (nonactivated) hydrolase activities. Essentially all endogenous lipase phosphatase could be removed by treatment of the pH 5.2 precipitate fraction with ATP-Sepharose affinity gel. The addition of a partially purified preparation of rat liver phosphorylase phosphatase deactivated triglyceride and cholesterol ester hydrolases. The deactivation process was concentration, 5 mM) and was inhibited by 5 mM phosphate and by phosphorylase alpha. Reversible deactivation of hormone-sensitive lipase alpha was also observed with crude prepa- and by phosphorylase alpha. Reversible deactivation of hormone-sensitive lipas alpha was also observed with crude preparations of phosphoprotein phosphatases from rat and turkey hearts, and from rat epididymal fat pads. Thus, hormone-sensitive lipase is deactivated by a variety of phosphoprotein phosphatases from different tissues and different species, implying a low degree of specificity for the deactivating system.
 ...
PMID:Role of phosphoprotein phosphatases in reversible deactivation of chicken adipose tissue hormone-sensitive lipase. 19 Feb 35

Levels of glucose-6-phosphate cyclase (myoinsitol-1-phosphate synthase, EC 5.5.1.4) and myoinositol-1-phosphate phosphatase (myoinositol-1-phosphatase, EC 3.1.3.25) were determined in extracts of testes from10-, 20-, and 30-day-old rats, and in extracts of Sertoli cells, germinal cells, and epididymides. The specific activity of the cyclase was approximately 1/10th that of the phosphatase in all extracts found to contain either enzyme. Among cells in the testis examined, Sertoli cells had highest levels of enzymes required for inositol biosynthesis from glucose, while spermatocytes and round spermatids did not have detectable activity. Spermatozoa from the epididymis also had no detectable cyclase or phosphatase activity. In contrast, extracts of washed epididymides contained exceedingly high specific activities of these enzymes. Primary cultures of Sertoli cells, maintained in a chemically defined medium without added inositol, released inositol into the medium during three successive 24-h periods. The amounts released were greater in cells stimulated by dibutyryl cyclic AMP. Results were interpreted to indicate that inositol in the fluid of seminiferous tubules most probably originates from Sertoli cells, which synthesize inositol from glucose. Additional inositol in the fluid of epididymal tubules could readily be provided by metabolism of glucose by epididymal epithelial cells
 ...
PMID:Myoinositol biosynthesis by Sertoli cells, and levels of myoinositol biosynthetic enzymes in testis and epididymis. 22 90

The influence of thyroid hormones on lipid biosynthesis was studied after administration of L-thyroxine to rats for 5 days. Their weights remained the same as those of control animals, despite an approximately 3-fold increment in plasma L-thyroxine and L-triiodothyronine concentrations. The activity of acetyl-CoA carboxylase and fatty acid synthetase as well as incorporation of tritium into fatty acids were depressed significantly in epididymal adipose tissue and enhanced significantly in livers of thyroxine-treated rats. Using antibodies specific against rat liver fatty acid synthetase, it was determined that the changes in activity of this multienzymic complex were due to alterations in amount of enzyme protein. In the presence of optimal concentrations of fatty acids, radioactive sn-glycero-3-phosphate, and co-substrates, total glycerolipid synthesis (defined in this study as the sum of newly formed radioactive mono- and diacyl-sn-glycero-3-phosphate, diglyceride, and triglyceride) was decreased significantly in adipose tissue and increased in liver and heart. Thus, administration of thyroid hormone results in tissue-specific alterations in lipid biosynthesis which, at least in the case of fatty acid synthetase, are due to changes in enzyme protein content.
 ...
PMID:Effects of thyroid hormones on enzymes involved in fatty acid and glycerolipid synthesis. 23 12

Female Swiss Webster mice were immunized intraperitoneally with mouse epididymal spermatozoa or with phosphate buffered saline (PBS) and their fertility was compared by (1) incidence and size of litters, (2) number of uterine implantation sites, and (3) incidence and number of fertilized eggs in the oviducts. Statistically significant reduction in fertility was noted following two courses of injections of spermatozoa; 12% of mice injected with spermatozoa had litters compared with 80% of mice injected with PBS. The infertility did not seem to be related to a failure in fertilization since the two groups of mice had a similar incidence and number of fertilized eggs in the oviducts. All female mice were found to have a "natural' anti-acrosomal antibody. Following immunization with spermatozoa, antibodies to "postacrosomal' region, the main piece and the midpiece of the tail, as well as cytotoxic antisperm antibodies, appeared. Anti-LDH-X antibody was not detected. However, correlation was not found between infertility and antisperm antibodies or sperm granulomata that developed in the peritoneal cavities. It is concluded that female mice receiving repeated i.p, injections of mouse spermatozoa become infertile and that the infertility is related to interference with events after fertilization.
 ...
PMID:Immunobiological consequence of immunization of female mice with homologous spermatozoa: induction of infertility. 39 94

Spermatozoa do not achieve full maturation and fertilizing capacity until passage through the epididymis. During this time they also gain motility, although spermatozoa do not move until after ejaculation. The organic fraction of human seminal plasma contains phosphate esters, particularly glycerylphosphorylcholine (GPC), phosphorylcholine (PCh), and inorganic phosphate (Pi). GPC is found in relatively high concentrations in the semen of many male animals, including man. GPC is synthesized by the epithelial cells of the epididymis, apparently under androgenic control. Consequently, it has been suggested that GPC might be a useful indicator of epididymal function. We have measured GPC, Pi, and PCh in fresh and frozen semen samples, using phosphorus nuclear magnetic resonance (31P NMR). All samples were assayed for phosphate esters. It was found that PCh was totally hydrolized to Pi. The average ratio of GPC to total phosphate (TP = GPC + Pi) remained constant at a value of about 0.1 for sperm counts over 20 million/ml. The ratio for azoospermic specimens was 0.02 or less; the same results were obtained from vasectomy specimens. This finding indicates that most of the GPC comes from the epididymis. There was a significant correlation between motility, progression, and the GPC ratio. Poor motility and progression in the specimens were accompanied by low GPC ratios regardless of the sperm counts.
 ...
PMID:The role of phosphate esters in male fertility. 71 Jun 5

1. Enzyme activities (units/g wet wt.) were determined in the caput and cauda epididymidis and in epididymal spermatozoa of the rat. 2. The activity of most enzymes in the cauda was between 50 and 100% of that in the caput, except that ATP citrate lyase was barely detectable in the cauda. 3. Spermatozoa, unlike epididymal tissue, contained sorbitol dehydrogenase but lacked ATP citrate lyase. NADP+-malate dehydrogenase, mitochondrial glycerol 3-phosphate dehydrogenase, succinate dehydrogenase, carnitine acetyltransferase and citrate synthase were 5 to 400 times as active in spermatozoa as in epididymal tissue. 4. 2-Oxoglutarate dehydrogenase was the least active member of the tricarboxylic acid cycle in all tissues and most closely matched the measured flux through the cycle. 5. The concentrations of hydroxyacyl-CoA dehydrogenase and carnitine palmitoyltransferase were equivalent to the more active enzymes of the tricarboxylic acid cycle, indicating the capacity for extensive lipid oxidation, and the presence of 3-hydroxybutyrate dehydrogenase suggests that these tissues can also oxidize ketone bodies. 6. Transfer of reducing equivalents from cytoplasm to mitochondrion is unlikely to occur by means of the glycerol phosphate cycle because mitochondrial glycerol 3-phosphate dehydrogenase is relatively inactive in epididymal tissue, whereas the cytoplasmic enzyme has little activity in spermatozoa, but transfer may be accomplished by the malate-aspartate shuttle. 7. Transfer of acetyl units from mitochondrion to cytoplasm could be effected by the pyruvate-malate cycle in the caput of androgen-maintained rats, but not in the other tissues because of the low activity of ATP citrate lyase. Acetyl unit transfer could take place via acetylcarnitine, mediated by carnitine acetyltransferase. 8. Castration resulted in a decrease in the concentration of nearly all enzymes, although subsequent administration of testosterone restored concentrations to values similar to those in animals maintained by endogenous androgen. The extent to which enzyme concentration was changed by an alteration in androgen status was highly variable, but was most marked in the case of pyruvate carboxylase.
 ...
PMID:Activity and androgenic control of enzymes associated with the tricarboxylic acid cycle, lipid oxidation and mitochondrial shuttles in the epididymis and epididymal spermatozoa of the rat. 72 83

Cauda epididymal sperm of mature guinea pigs were incubated (37 degrees, 5% CO2 in air). 10% of the total enzyme activity was released into the medium in 4 hr, 30% in 24 hr. Addition of lysolecithin resulted in rapid release of hyaluronidase. Vitamin C (0.54 mM), sodium fluoride (0.02 M), and cholesterol increased the rate of release whereas citrate (20 mM) diminished it. No effect upon hyaluronidase release was noted upon addition of KCN (10(-2)M), progesterone (250 microgram/ml), testosterone (500 microgram/ml), spermine (1.15 mg/ml), inositol (5.6 mM), or chloroquine phosphate (0.54 mM).
 ...
PMID:Hyaluronidase release from guinea pig spermatozoa as affected by reproductive tract secretions and metabolic inhibitors. 73 70


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