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)

The presence of androgen-binding activity in cytosol prepared from the major anatomical segments (caput, corpus, and cauda) of the epididymis of castrated sexually mature rabbits has been demonstrated. A portion of this binding activity is likely to be the epididymal androgen receptor. When epididymal cytosol from adult castrated rabbits is analyzed on low-ionic strength (0.01 MKCl) sucrose gradients, two peaks of macromolecular binding could be detected, one congruent to 4.6S and one congruent to 8S. On gradients containing 1.0 M KCl, only one sedimenting form congruent to 4.6S could be demonstrated, suggesting that the 8S component is composed of aggregates. If cytosol was preincubated with labeled androgen, followed by an incubation with unlabeled androgen, and subsequently analyzed for binding on low-ionic strength gradients, only the congruent to 8S peak could be detected, indicating that most of the binding in the congruent to 4.6S region was rapidly dissociable. This suggests that binding in this region was to moieties other than receptor. Since androgen binding proteins (ABP) of testicular origin would have been cleared from the epididymis at the timepoints that we concentrated on for most of these studies, the 4.6S binding probably represents the association of androgen with plasma testosterone binding globulin (TeBG). The binding of androgen to the receptor can be inhibited by cyproterone, while this antiandrogen does not inhibit binding to either ABP or TeBG at the concentration used.
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PMID:Androgen binding to cytosol prepared from epididymides of sexually mature castrated rabbits: evidence for a cytoplasmic receptor. 16 97

There appear to be two classes of protein kinases in rat heart and adipose tissue, types I and II. Type I elutes from DEAE-cellulose at smaller than 0.1 M NaCl and type II at greater than 0.1 M NaCl. The type I enzyme is more readily dissociated by salt or histone than is the type II enzyme. If the type I kinase is first dissociated by cAMP, the subunits reassociate very slowly at 0 degrees C on removal of the cAMP by Sephadex G-25 chromatography, whereas those of type II reassociate very rapidly. Rat heart contains mostly type I and a small amount of type II enzyme, whereas adipose tissue contains almost exclusively the type II enzyme. The adipose tissue enzyme resembles the heart type II kinase in all of the above properties, although the two enzymes are not identical as indicated by slight differences in elution patterns from DEAE-cellulose columns. Incubation of rat epididymal adipose tissue with low concentrations of epinephrine (0.11 muM) increases glycerol production and the fraction of the protein kinase in the active form (activity ratio). The change in cAMP under these conditions is not statistically significant. The presence of insulin inhibits the epinephrine effect on glycerol production and protein kinase but has no measurable effect on cAMP levels. Incubation of adipose tissue with high epinephrine concentrations (11 muM) increases the cAMP level, the protein kinase activity ratio, and glycerol production. Under these conditions insulin decreases the cAMP level and kinase activity ratio but does not reduce glycerol production. The data suggest that very small changes in the tissue cAMP level, undetectable by the assay method, are magnified during the stepwise activation of glycerol output aided possibly by cooperative effects between cAMP and protein kinase. The procedure developed for determining the state of activation of the cAMP-dependent protein kinase in adipose tissue must be modified by reducing the salt concentration of the buffers in order to carry out similar studies in the heart. This reflects the different types of protein kinase in the two tissues. The addition of charcoal to crude extracts of heart prevents protein kinase activation by added cyclic AMP. Charcoal should therefore prevent any activation that could occur if any sequestered cAMP were released during homogenization. Charcoal addition thereby provides a means to distinguish intracellular cAMP activation of the kinase from that which might occur following cell rupture. If epinephrine-perfused hearts are homogenized in the presence of charcoal, epinephrine stimulation of the protein kinase is only slightly decreased. This indicates that the protein kinase is activated intracellularly by cAMP and suggests that all of the cAMP in the cell is available to the protein kinase; i.e., cAMP is not released during homogenization.
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PMID:Hormonal regulation of adenosine 3',5'-monophosphate-dependent protein kinase. 16 70

Rat epididymal tubules maintained in organ culture for 3 days respond to the addition of androgens to the culture media (testosterone and dihydrotestosterone 1 x 10-minus 5 m and 1 x 10-minus 7 m) with an increased incorporation of amino acids into acid-insoluble material. Significant androgenic stimulation is observed only 24 h after addition of hormone, while an inhibitory effect is found at earlier periods. The stimulation seems to be specifically produced by androgens; it is blocked by cyproterone acetate and is not elicited by oestradiol-17beta or corticosterone. The process appears to involve RNA synthesis since actinomycin D suppresses the stimulatory effect of androgen. Evidence suggests that cAMP production is not a primordial step in the response to androgen since dibutyryl cAMP did not mimick the androgenic effect, theophylline did not potentiate the response and alpha,beta-methylene ATP, which competitively inhibits adenyl cyclase, failed to alter the androgenic effect. Radioactive testosterone and dihydrotestosterone added to the culture media showed a preferential intranuclear localization as well as extensive metabolism. DHT was found to be the principal intranuclear steroid.
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PMID:The influence of androgens on protein synthesis by cultured rat epididymal tubules. 16 37

Human chorionic somatomammotropin extracted and purified from placenta at term was proved to have a lipolytic action in the epididymal fat pad of rats. The following mechanism appears to be involved in the lipolytic action of the hormone; human chorionic somatomammotropin activates adenyl cyclase, thereby increasing the concentration of cyclic AMP in the tissue, which, in turn, activates protein kinase to lead to the activation of hormone sensitive lipase.
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PMID:Lipolytic action of human chorionic somatomammotropin. 16 57

Testicular androgen-binding proteins (ABP) in rabbit testis, caput epididymis and efferent duct fluid (EDF) were compared to a similar androgen-binding protein TeBg) in rabbit serum. The affinity of these proteins for 5alpha-dihydrotesterone (DHT) at 0 degrees C (KaABP = 1.6 X 10(9) M-1 and KaTeBG = 1.9 X 10(9) M-1) and their steroid specificities were similar (DHT greater than androstanediol greater than progesterone and androstenedione). ABP and TeBG had also almost identical Stokes radii (42.8 +/- 1.2 and 43.9 +- 0.8 A, respectively), sedimentation coefficients (4.7 +/- 0.2 S and 4.4 +/- 0.2 S, respectively) and electrophoretic mobility (Rf = 0.4 in 6 1/2% polyacrylamide gels). Calculation of molecular weights from Stokes radii and sedimentation rates indicated a molecular weight of 74,000 (69,000-78,000) for TeBG and 76,000 (71,000-82,000) for ABP. The corresponding frictional ratios were 1.61 for TeBG and 1.55 for ABP assuming a partial specific volume (v) of 0.70 cm3/g. Polyacrylamide gel electrophoresis (PAGE) at different gel concentrations gave a mean molecular radius of 2.74 nm, also indicating a molecular weight of about 75,000 (v = 0.70 cm3/g. ABP and TeBG could not be separated by PAGE; however, partial separation of ABP and TeBG was achieved by isoelectric focusing and ion-exchange chromatography on DEAE-cellulose. TeBG focused at pH 5.4, whereas ABP formed a distinct peak of bound radioactivity at pH 4.7. Also by ionexchange chromatography, ABP in both testis and epididymal supernatants was shown to have an apparently higher surface charge than TeBG in rabbit serum. The concentration of ABP in efferent duct fluid (2 X 10(-7) M = 60 pmol/mg protien) was much higher than TeBG in male rabbit serum (5.2 X 10(-8) M = 0.7 pmol/mg protein). These findings ruled against the possibility that ABP in the testis and epididymis could have been derived directly from serum. It is concluded that ABP and TeBG are very similar if not identical proteins both serving as transport and carrier proteins in their respective compartments.
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PMID:Testicular androgen-binding protein (ABP): comparison of ABP in rabbit testis and epididymis with a similar androgen-binding protein (TeBG) in rabbit serum. 16 2

A connecting link between carbohydrate and fat metabolism in adipose tissue is theconcentration of alpha-glycerophosphate derived predominantly from the glycolysis ofglucose entering the fat cell. However, several investigators have reported the presence of a glycerol specific kinase in the epidiymal fat-pad of the rat and obob mouse. This enzyme's presence in other mammalian adipose tissue could contribute to the alpha-glycerophosphate pool and thus affect both carbohydrate and fat metabolism within the fat cell. Glycerokinase was demonstrated in isolated fat cells obtained from the subcutaneous, perirenal, epididymal, and dorsal intrascapular brown fat depots of the adultmale rat. It was found to be particularly sensitive to in vivo lipogenic stimuli in both the subcutaneous and the brown adipose tissue and concluded that insulin is involved in adipose glycerokinase stimulation. Therefore, the main function of glycerokinase in normal adipose tissue may be to augment the anabolic action of insulin. It isfurther suggested that deviation from the normal control of this lipogenic enzyme couldlead to a gradual accumulation of fat and eventual obesity.
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PMID:Glycerokinase in mammalian adipose tissue: stimulation by lipogenic substances. 16 85

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.
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PMID:Activation of pyruvate dehydrogenase in adipose tissue by insulin. Evidence for an effect of insulin on pyruvate dehydrogenase phosphate phosphatase. 16 82

The normal weight increase of the epididymis during sexual maturation and its maintenance through adulthood were found to be dependent on the provision of androgens. Binding of [3H]dihydrotestosterone (DHT) to the epididymal 8S cytoplasmic receptor gradually decreased after castration to become undetectable after 25 days. Binding to the androgen binding protein (ABP) was absent 4 days after castration and was not reinduced by 3 weeks of testosterone (T) administration. Unilateral castration for periods of up to 27 days showed the disappearance of ABP with preservation of the 8S receptor on the castrated side, indicating a testicular source for ABP and the epididymal origin of the 8S receptor. The tissue concentrations of T and DHT in the epididymis became undetectable 30 days after castration and were restored to normal values by administration of testosterone in large doses (1.5 mg/100 g BW). Similar results were obtained in rats castrated at 10 days of age and injected with testosterone until 60 days old. The ratio DHT/T was depressed in the castrate and increased with testosterone treatment. The protein content of the epididymis (mg of protein/g wet weight) was also found to be influenced by androgens. Our results show evidence of some mechanisms involved in the trophic effect of androgens upon the epididymis and suggest the possible androgenic control of epididymal 5alpha-reductase activity. They also indicate that a testicular factor is required for the maintenance of the 8S cytoplasmic androgen receptor. It is not known whether this factor is testosterone or some other testicular secretion.
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PMID:The effect of castration and testosterone replacement on specific proteins and androgen levels of the rat epididymis. 16 24

After i.m. injection of [3H]butyrobetaine into rats, the accumulation of carnitine into the epididymis, prostate gland, seminal vesicles, testis and heart was studied. The concentration of radiolabeled carnitine into the cauda epididymis increased linearly with time up to 72 h after the injection of the precursor, while its level in the prostate and seminal vesicles decreased rapidly. Very low levels of carnitine were found in the testis. Castration reduced the carnitine accumulation by cauda epididymis to 6% of the control levels while treatment of castrated animals with testosterone propionate (500 mug/day) partly restored the carnitine uptake. Similar treatment with 17beta-oestradiol valerate or 17alpha-hydroxyprogesterone had no effect. Surprisingly, cyproterone acetate (5 mg/day) also significantly stimulated carnitine accumulation by the epididymis to a level above that of the castrated controls. Simultaneous injection of both cyproterone acetate and testosterone propionate to castrated animals caused an additive effect of these steroids. This indicated that cyproterone acetate in this system is working as a weak androgen. Treatment of rats with 17beta-oestradiol valerate also reduced carnitine accumulation by the cauda epididymis. This is due to suppression of pituiatry gonadotrophin secretion, since concommitant treatment with testosterone propionate (500 mug/day) caused a normalization of the carnitine uptake. Treatment of intact rats with cyproterone acetate significantly reduced the epididymal weight, but not the carnitine accumulation. 17alpha-Hydroxyprogesterone treatment had no effect either on the epididymal weight or the accumulation of the carnitine. Unilateral orchiectomy reduced the carnitine accumulation by the cauda epididymis to about 40% of that occurring in the non-operated control side. This indicates that the luminal contact between the testis and epididymis or the luminal content of the epididymis itself is of importance for the androgen-dependent metabolic process occurring in the cauda epididymis. Castration or hormone treatment did not change the conversion of butyrobetaine to carnitine, or the carnitine uptake by heart. Carnitine uptake by the testis after [3H]butyrobetaine injection was rather low and this would exclude the possibility of synthesis of carnitine in the testis as a source of epididymal carnitine. Carnitine only accumulated in the cauda epididymis in vivo 4 to 96 h after injection of [3H]butyrobetaine. The presence of radioactively labeled butyrobetaine or methylcholine was not detected.
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PMID:Androgen-dependent accumulation of carnitine by rat epididymis after injection of [3H]butyrobetaine in vivo. 17 Jan 50

The cytoplasmic recptor (CR) in rat epididymal 105,000 g supernatant was separated from the androgen-binding protein (ABP) by gel electrophoresis following labeling with [1,2,6,7-3H]-testosterone in vivo. ABP disappeared from epididymal supernatants after castration of hypophysectomy, while CR remained unchanged. CR was evenly distributed between caput and cauda, while much more ABP was present in caput. Properties of CR in epididymis and prostate were similar and distinctly different from ABP. Binding to CR was destroyed by charcoal treatment (1 mg/mg protein) of supernatant for 0 degrees C for 6 h, heating at 50 degrees C for 30 min, or exposure to the sulfhydryl blocking reagent, p-chloromercuriphenylsulfonate (1mM) at 25 degrees C for 30 min, while binding to ABP was unaffected. The isoelectric pH of CR (5.8) was higher than that of ABP (4.6). Dissociation of radioactive 5alpha-dihydrotestosterone (DHT) from CR and nuclear receptors was extremely slow (half-time at 0 degrees C is greater than 2 days), while dissociation from ABP was rapid (half-time at 0 degrees C is similar to 6 min). Cyproterone acetate (250 mg/100 g body weight) inhibited binding to CR both in epididymis and ventral prostate but did not affect binding to ABP. Nuclear uptake was inhibited by cyproterone to the same extent as binding to CR, indicating that nuclear uptake and binding are dependent on CR and independent of ABP. The time-course of uptake and binding in epididymal supernatant and nuclear fractions was essentially the same 1 day after bilateral castration when both CR and ABP were present or 8 days after castration when CR alone was present. It is concluded that the cytoplasmic receptor for androgen in rat epididymis has properties very similar to the androgen receptor in ventral prostate but different from ABP.
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PMID:Androgen-binding proteins in rat epididymis: properties of a cytoplasmic receptor for androgen similar to the androgen receptor in ventral prostate and different from androgen-binding protein (ABP). 17 Jan 53


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