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)

Epididymal 5alpha reductase activity was found distitributed in the crude nuclear fraction (44 percent) and microsomal fraction (41 percent). Spermatozoa contaminating the nuclear preparation accounted for only 3 percent of its activity. There were no regional differences in the distribution of total 5alpha reductase activity. However, the nuclear enzyme was more active in caput than in other regions. Maximal activity was found at pH 6.2 and at 32 degrees C. Both enzymes had an absolute requirement of reduced dinucleotides. The microsomal preparation could only us NADPH while the nuclear enzyme could use NADPH and NADH. The apparent Km for the microsomal preparation was 0.62 +/- 0.05 X 10(-6)M and Vmax was 555 +/- 38 pmoles/mg protein/hour. The nuclear enzyme presented similar values. The reaction was not inhibited by accumulation of product in the medium, but other steroids such as progesterone, epitestosterone (17alpha-hydroxy-4-androsten-3-one) and 3-oxo-4-androstene-17beta-carboxylic acid were potent competitive inhibitors. The reaction was strongly inhibited by Hg, Zn and Cu. The properties of the epididymal reductase are similar to those of the prostatic enzyme.
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PMID:Partial characterization of epididymal 5 alpha reductase in the rat. 2 73

As it was shown previoulsy by others, the membrane-bound phosphodiesterase (cyclic adenosine 3':5'-monophosphate phosphodiesterase) of rat epididymal fat cells was stimulated when intact cells were exposed to insulin. The levels of stimulation observed in the present study in the cell homogenate and microsomal fraction were approximately 2.0- to 2.5-fold and 2.5- to 3.0-fold, respectively, when the initial substrate level was 100 nM and insulin concentration was 1 to 3 nM. When the microsomal fraction was subjected to a sucrose density gradient centrifugation, most of the insulin-sensitive phosphodiesterase activity was fractionated into the "light" microsomal fraction which was rich in NADH2:potassium ferricyanide:oxidoreductase) and low in 5'-AMPase, adenylate cyclase, and insulin-binding activities. The latter three activities were mostly fractionated into the "heavy" microsomal fraction. Both basal and insulin-stimulated phosphodiesterase activities were low when cells were homogenized in the presence of N-ethylmaleimide or p-chloromercuribenzoate. The insulin-stimulated enzyme activity was also low when cells were homogenized in the presence of --SH compounds (e.g. dithiothreitol) or certain metal-chelating agents (e.g. ethylene glycol bis(beta-aminoethyl ehter)-N,N'-tetraacetate (EGTA)), or in a nitrogen atmosphere. The effect of EGTA was prevented by the addition of certain heavy metal ions but not by the addition of Ca2+ or Ca2+ plus Mg2+ ions. When cells were homogenized in the presence of certain oxidants (e.g. diamide, sodium tetrathionate, or air), a high plus-insulin activity was observed; this activity was not lowered by subsequent treatment of the enzyme with N-ethylmaleimede, EGTA, or fresh cell homogenate that was prepared in the presence of EGTA. However, the activity of an apparently oxidized enzyme could still be lowered by treatment woth dithiothreitol. A partially purified enzyme in the enzyme in the microsomal fraction was fairly stable both in basal and insulin-stimulated states (fully active after 35 days when kept at -20degrees). EGTA added to the homogenization buffer lowered the basal phosphodiesterase activity, but this effect was reversed by the addition of Ca2+ ions. EGTA also decreased the enzyme activity that was stimulated by norepinephrine. However, neither EGTA nor dithiothreitol had any effect on the activities of 5'-AMPase, NADH-dehydrogenase, and malate dehydrogenase of fat cells. The above data indicate that most of the insulin-sensitive phosphodiesterase and the so-called "cell membrane markers" are associated with different subcellular particles in the cell homogenate. In addition, the data seem to indicate that the insulin-stimulated phosphodiesterase has certain --SH groups and that the activity of the enzyme is stabilized when the --SH groups are oxidized by certain oxidants including molecular oxygen. It is suggested that the air oxidation of the enzyme is catalyzed by a trace of certain heavy metal ions and, therefore, can be blocked by a metal-chelating agent.
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PMID:Insulin-sensitive phosphodiesterase. Its localization, hormonal stimulation, and oxidative stabilization. 17 Feb 71

Aromatization was measured in testicular microsomal preparations obtained from rats treated 3--4 days with FSH, hCG, or vehicle, hCG, but not FSH, was found consistently to stimulate testicular aromatase activity at least 10-fold. As a marker for FSH action, epididymal androgen-binding protein was assayed and found to be 3 times higher in FSH-treated rats than in either hCG or control rats. hCG, but not FSH or vehicle, stimulated serum testosterone levels more than 100-fold. In all groups, aromatase activity in the microsomal fraction was at least 6 times higher than that found in the mitochondrial fraction. In experiments in which testicular compartments were separated, microsomal preparations from interstitial tissue of hCG-treated rats had 5--7 times more aromatase activity than microsomes from seminiferous tubules and 2--3 times more activity than microsomes from whole testes. It is concluded the hCG administered in vivo can stimulate testicular aromatase activity in immature rats, and the increase in activity is localized in the interstitial tissue.
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PMID:Testicular aromatization in immature rats: localization and stimulation after gonadotropin administration in vivo. 57 93

Subfractionation of the fat free homogenate of rat adipose tissue showed that a high yield of triglyceride lipase was recovered reproducibly in the microsomal supernatant fraction (cytosol) when rat epididymal fat pads were homogenized in sucrose-EDTA-Tris medium. Triglyceride lipase was bound on heparin-Sepharose. Hydrolyzing activity towards triacylglycerol was eluted as a single, sharp peak in 0.7 M NaCl, 5 mM sodium barbital and 20% glycerol (pH 7.0). The triglyceride lipase was not inhibited by 1 M NaCl and not stimulated by the presence of fresh human serum. A lipoprotein-lipase activity was demonstrable in the cytosol when adipose tissue from fed rats were used. Fasting of the animals lowered this activity.
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PMID:Affinity chromatography on heparin-sepharose of rat adipose tissue triglyceride lipase from cytosol. 66 59

This study supports the possibility for multiple subcellular forms of lipoprotein lipase. 1. The total activity of lipoprotein lipase per g of intact epididymal adipose tissue from fed rats is much higher than that from starved rats. 2. The isolated fat-cells of fed and of starved rats have lipoprotein lipase of almost the same activity per g of fat-pads. The isolated fat-cells of starved rats have a much higher proportion of total activity per g of the intact tissue than do those of fed rats. 3. Under the conditions of homogenization used, only a small proportion of the total activity per g of intact tissue from fed rats was associated with the fat layer which floated to the top of the homogenate during low-speed centrifugation. The different proportions of the specific enzyme activity found in each subcellular fraction are described. 4. Lipoprotein lipase from plasma membranes and microsomal fractions from starved and fed rats was purified by affinity chromatography. 5. The total activity of microsomal lipoprotein lipase per g of intact adipose tissue is enhanced by a normal diet. 6. In intact epididymal adipose tissue from fed rats, the activity per g of tissue of lipoprotein lipase of plasma membranes is much higher than that in the same fraction from starved rats. By contrast, the activities per g of tissue in plasma membranes obtained from starved or from fed rats by collagenase treatment were similar.
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PMID:Effect of nutrition on subcellular localization of rat fat-cell lipoprotein lipase. 66 42

To understand the molecular mechanisms responsible for the sepsis-induced enhanced glucose uptake, we have examined the levels of GLUT4 and GLUT1 mRNA and protein in the adipose tissue of septic animals. Rats were challenged with a nonlethal septic insult where euglycemia was maintained and hexose uptake in adipose tissue was markedly elevated. Northern blot analysis of total RNA isolated from epididymal fat pads indicated differential regulation of the mRNA content for the two transporters: GLUT1 mRNA was increased 2.6 to 4.6-fold, while GLUT4 mRNA was decreased by 2.5 to 2.9-fold. Despite the difference in mRNA levels, both GLUT1 and GLUT4 protein were down regulated in plasma membranes (40% and 25%, respectively) and microsomal membranes (42% and 25%, respectively) of the septic animals. The increased glucose uptake cannot be explained by the membrane content of GLUT1 and GLUT4 protein. Thus, during hypermetabolic sepsis, increased glucose utilization by adipose tissue is dependent on alternative processes.
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PMID:Differential regulation of glucose transporter gene expression in adipose tissue or septic rats. 155 May 51

A cDNA clone encoding androgen-dependent proteins secreted by the mouse epididymis was isolated by screening a cDNA library using differential hybridization, according to the selective expression of the mRNA in the normal but not in the castrated mouse. Translation of mRNA hybrid-selected by this 1.4 kb clone (M53) yielded proteins of Mr 26,000 which were processed in vitro in the presence of microsomal membranes into proteins of Mr 24,000. Northern blot analysis of epididymal total RNA revealed at least two populations of mRNA (1.4 and 1.8 kb) homologous to the M53 clone, which were restricted to the caput epididymidis. Studies in vivo demonstrated that testosterone regulates the concentration of these mRNA populations. Analysis of epididymal total RNA from ten individual animals provided no evidence that the M53 mRNA populations are the products of allelic variants of a gene. Southern analysis of mouse genomic DNA revealed single bands with most of the tested restriction enzymes. Furthermore, cross-hybridization to the M53 cDNA revealed homologous mRNA species in rat, human, rabbit, ram and boar epididymal RNA.
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PMID:Molecular cloning of a cDNA for androgen-regulated proteins secreted by the mouse epididymis. 232 85

Receptors for insulin-like growth factor II (IGF-II) have been compared in solubilized microsomal membranes from rat lung, brain, kidney, heart, epididymal and subcutaneous fat, ovary, testis and adrenals. Highest binding/microgram protein was seen with testicular membranes. Receptors from all tissues showed high affinity for human IGF-II (mean association constant = 65 litres/nmol) and a high degree of specificity (mean IGF-I cross-reactivity 0.3%; no cross-reactivity with insulin). Affinity labelling followed by sodium dodecyl sulphate polyacrylamide gel electrophoresis showed binding was only to a type-II IGF receptor, with a major band seen at a molecular weight of about 230,000 in lung, brain, kidney and testis, and 240,000 in heart, fat and adrenal gland. All tissues showed broad or bimodal pH dependence of binding, with optima seen at about pH 6 and pH 9. Mild stimulation of IGF-II binding by low calcium concentrations (1-2 mmol/l) was seen in all tissues, although higher concentrations were inhibitory in the brain. It was concluded that IGF-II receptors from different rat tissues, when studied under uniform conditions, show similar binding affinities but differences in size and regulation which might be missed if receptors are examined in separate studies.
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PMID:Comparison of receptors for insulin-like growth factor II from various rat tissues. 295 36

The subcellular distribution of Mg2+-dependent phosphatidate phosphohydrolase in rat adipocytes between a soluble and a membrane-bound fraction was measured by using both centrifugal fractionation and a novel Millipore-filtration method. The relative proportion of the phosphohydrolase associated with the particulate fraction was increased on incubation of cells with noradrenaline or palmitate. Insulin on its own decreased the proportion of the phosphohydrolase that was particulate and abolished the effect of noradrenaline, but not that of palmitate. The effect of noradrenaline on phosphohydrolase distribution was rapid, the effect being maximal within 10 min. Noradrenaline exerted this effect with a similar concentration-dependence to its lipolytic effect. Inclusion of albumin in homogenization buffers decreased the proportion of the phosphohydrolase that was particulate, but did not abolish the effect of noradrenaline. There was limited correlation between the proportion of the phosphohydrolase that was particulate and the measured rate of triacylglycerol synthesis in adipocytes incubated under a variety of conditions. Starvation, streptozotocin-diabetes and hypothyroidism decreased the specific activities of the phosphohydrolase and glycerolphosphate acyltransferase in homogenates from epididymal fat-pads. Restoration of these activities in the diabetic state was seen after administration of insulin over 2 days or, in the short term, within 2 h after a single administration of insulin. Administration of thyroxine over 3 days caused restoration of these activities in the hypothyroid state. Starvation and diabetes increased the proportion of the phosphohydrolase found in the microsomal fraction. This change was not seen when albumin was present in homogenization buffers. The possible role of fatty acids as regulators of the intracellular translocation of the phosphohydrolase, together with the role of this enzyme in the regulation of triacylglycerol synthesis in adipose tissue, is discussed.
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PMID:Adipose-tissue Mg2+-dependent phosphatidate phosphohydrolase. Control of activity and subcellular distribution in vitro and in vivo. 302 68

1. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) produces atrophy, morphological changes, impaired spermatogenesis, and epididymal lesions in testis of experimental animals. The effects of TCDD administration to male rats on various parameters in the testes were examined. 2. Nine days after TCDD administration, significant decreases in body and testes weights occurred. However, the testes weight as a percent of body weight was higher in treated than control animals. 3. An increase in lipid peroxidation (content of thiobarbituric acid reactive substances) occurred in conjunction with the decrease in testicular weights. 4. TCDD administration produced a 3-fold increase in protein kinase C activity, small but significant decrease is superoxide dismutase and glutathione peroxidase activities, and no effect on catalase, glutathione reductase or glutathione S-transferase activities in the testes. 5. Nine days after treatment with TCDD, in the testes the iron content of whole tissue and cytosol increased while a decrease in microsomal iron was observed. The copper content of mitochondria and microsomes decreased with a corresponding increase in cytosol copper content. A small increase in the zinc content of whole testes occurred. 6. The data indicate that testicular atrophy due to TCDD may be associated with lipid mobilization and peroxidation.
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PMID:2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)-induced alterations in lipid peroxidation, enzymes, and divalent cations in rat testis. 324 26


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