UNIPROT:P56851 - FACTA Search

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Query: UNIPROT:P56851 (epididymal)
11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During our studies on the active moiety of parotin, we succeeded in purifying MP-parotin (MW = 130000) and parotin-subunit (MW = 45000) from crude parotin. Furthermore, AA-1 (MW = 9100) was isolated after the tryptic cleavage of the parotin-subunit. AA-1 was the smallest unit ever obtained which had serum Ca-decreasing activity and circulating leucocyte-increasing activity together with the nature of specific localization in bone. Therefore, AA-1 was considered to contain the essential residues for parotin activity in its structure. Since crude parotin was also known to show andromimetic action, these parotin components reduced in size were assayed in this regard. A daily injection of MP-parotin (500 micrograms/kg), parotin-subunit (20 micrograms/kg) or AA-1 (20 micrograms/kg) was administered subcutaneously for two weeks to male rats weighing 200 approximately 220 g. The dynamics of the testicular biosynthesis of testosterone from 3H-pregnenolone and 14C-progesterone via delta 4, delta 5-pathway and the transition of delta 5 to delta 4-steroids were measured. MP-parotin and the parotin-subunit stimulated the pathway of pregnenolone----17-hydroxypregnenolone----dehydroepiandrosterone---- androstenedione----testosterone and resulted in the elevation of serum testosterone levels. Cyclic AMP levels in the testicular homogenate and the motility of epididymal sperm were also increased by the treatment. On the other hand, AA-1 showed no effect on these parameters. It was concluded that andromimetic activity, which is involved in MP-parotin or parotin subunit was independent of parotin activity on the bone tissue.
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PMID:[The effects of parotin components on testosterone biosynthesis in rats]. 632 59

The effects of adenylate cyclase inhibition on the transport of glucose and fructose and their incorporation into glycogen were investigated in order to assess the extent to which lowered cAMP levels can take part in the various components of glycogen synthesis regulation in isolated rat epididymal adipocytes. The dose-response characteristics of (R)-N-(2-phenylisopropyl)adenosine (PIA), a potent and specific adenylate cyclase inhibitor, on glycogen synthesis were compared with those effectively inhibiting lipolysis, a measure of functional cAMP levels. PIA had no effect on basal glucose or fructose transport but stimulated glucose and fructose incorporation into glycogen. Their respective incorporation was 10 and 69% of that achieved in the presence of insulin. These effects of PIA were shown to be in part the result of increased glycogen synthase I activity. PIA was 20% as effective as insulin in this action. Thus, were insulin to lower cAMP levels and/or inhibit cAMP-dependent protein kinase, this action would be irrelevant to glucose transport but would contribute to the stimulation of glycogen metabolism. However, an additional mechanism(s) involving neither increased glucose transport nor lowered cAMP levels is required to account for the full action of insulin. Fat cells in the absence of medium glucose and in the presence of 10(-7) M PIA and adenosine deaminase constitute a system functionally depleted of cAMP where this mechanism can be studied in isolation.
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PMID:Glycogen synthesis stimulation by adenylate cyclase inhibition in rat epididymal adipocytes. 634 22

Out of the publications of the last three years concerning the influence of the epididymis on the male fertility those with practical relevance were reviewed. Several qualities of the spermatozoa were influenced by the epididymis: the metabolism, the functions of cell membrane, the fertilizing capacity, the ability to bind to zonae pellucidae of the oocytes and the motility. The motility depends on the electrolytes, androgenes, cAMP-system and the forward motility protein in the epididymis. Furthermore investigations exist dealing with the inhibition of the maturation of spermatozoa during the epididymal transit as a mean of contraception. The conclusion is supported that male fertility demands only a weak or a reversible disturbance of the epididymis. An other possibility would be the in vitro maturation of testicular spermatozoa.
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PMID:[Effect of the epididymis on male fertility]. 654 55

The ejaculated porcine spermatozoa were fractionated into the cytosol, membrane, midpiece plus tail (flagella) and head fractions, and their adenylate cyclase activities were measured. About 65% of the total activity was located in the flagella fraction. For all the fractions, Mn2+-dependent adenylate cyclase activity was about 20 times higher than Mg2+-dependent activity, and guanine nucleotides, fluoride, and other reagents tested did not activate adenylate cyclase. The results suggest that the GTP-dependent regulatory subunit is absent in porcine spermatozoa. The porcine seminal plasma was found to stimulate the adenylate cyclase activity in spermatozoa. The stimulating factor in porcine seminal plasma was partially purified by gel filtration and the molecular weight of the factor appeared to be between 200 and 300. The partially purified factor is heat stable and is not inactivated by treatment with Pronase, trypsin, phospholipase A2 or D but is inactivated by acid hydrolysis. It is easily soluble in water, partially soluble in methanol, and insoluble in ethanol, ethyl ether, chloroform, or acetone. The activation of sperm adenylate cyclase by the factor occurred without a time lag. The activating effect was dose-dependent, saturated at high dose, and ascribed to the increase of the maximal velocity (Vmax). The effect of the factor appears to be limited to adenylate cyclase in spermatozoa; the factor activated adenylate cyclase both in porcine and bovine spermatozoa but failed to activate those in other porcine tissues. The factor was shown to activate the enzyme not only in the ejaculated spermatozoa but also in the epididymal sperm. The factor was also found to elevate the cAMP level in the intact porcine spermatozoa. The factor enhanced the motility of corpus and cauda epididymal spermatozoa. These findings indicate the possibility that this factor initiates the spermatozoan motility upon ejaculation through directly activating adenylate cyclase.
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PMID:Activation of spermatozoan adenylate cyclase by a low molecular weight factor in porcine seminal plasma. 663 Feb 19

Diurnal changes in glycogen stores of adipose tissues and in vitro lipolytic activity of isolated epididymal fat cells, and their lipolytic responsiveness to epinephrine and theophylline were examined in rats adapted to a 2-h daily meal feeding (20.00-22.00 h; darkness between 20.00-08.00 h) for 3 weeks and in control rats fed ad libitum. The fat cells from both groups of animals showed the peak of lipolytic activity at the mid-dark period (03.00 h), but the peak values and the average values at 6 or 7 time points examined within the 24-h feeding cycle were significantly higher (p less than 0.025) in meal-fed rats. Basal, epinephrine-stimulated, and epinephrine-induced lipolysis of fat cells from control rats showed diurnal changes, and the rhythms and their amplitude were affected by meal feeding. Changes in lipolytic activity of fat cells did not seem to relate directly to those of glycogen stores in adipose tissue. The over-all 24-h means of lipolytic activity of fat cells were significantly increased (p less than 0.001) with meal feeding. Mean cell size of epididymal fat pads was significantly smaller (p less than 0.001) in meal-fed rats, but lipolytic responsiveness to the graded concentrations of epinephrine and theophylline in the incubation medium was significantly greater (p less than 0.001) in meal-fed rats than in rats fed ad libitum. Thus, these findings suggest that lipolytic activity of the cAMP-hormone sensitive lipase system in fat cells might be increased with meal feeding in rats. Furthermore, the present results may give a new idea to consider the discrepancy that many workers have not been able to observe the increase in body fat deposition with meal feeding, which has been frequently reported to enhance lipogenesis in rats.
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PMID:Diurnal changes in lipolytic activity of isolated fat cells and their increased responsiveness to epinephrine and theophylline with meal feeding in rats. 668 56

The effects of growth hormone (GH) and testosterone, alone or in combination, on the regulation of lipolysis in isolated adipocytes from hypophysectomized rats were investigated. Male Sprague-Dawley rats were hypophysectomized at 50 days of age. One week after operation, hormonal replacement therapy with L-thyroxine and hydrocortisone acetate was given to hypophysectomized rats. Groups of rats were treated with GH (1.33 mg/kg, daily), testosterone (10 mg/kg, once) alone or in combination. After one week of hormonal treatment, adipocytes were isolated from the pooled epididymal and perirenal fat pads and glycerol release after isoproterenol stimulation and 125I-cyanopindolol binding was measured. Hypophysectomy caused a marked decrease in basal and isoproterenol-stimulated lipolysis. There was no effect of testosterone treatment alone on lipolysis, but GH treatment resulted in an increase in isoproterenol-induced lipolysis but not to the levels observed in cells from control rats. Testosterone and GH in combination restored the lipolytic response to isoproterenol. Also 125I-cyanopindolol binding was decreased after hypophysectomy. Testosterone treatment alone and GH treatment alone increased the binding, while in combination the treatment had an additive effect. Affinity was not changed, but the effects seemed to be on receptor number, as determined by Scatchard analysis. Forskolin-stimulated cAMP accumulation in adipocytes was markedly reduced after hypophysectomy. Testosterone treatment alone had no effect. GH treatment alone increased forskolin-stimulated cAMP accumulation, although the level was lower than that found in control rats. The combined treatment resulted in a further increase to levels observed in adipocytes from control rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Additive effects of growth hormone and testosterone on lipolysis in adipocytes of hypophysectomized rats. 749 May 28

In the accompanying report (Visconti, P.E., Bailey, J.L., Moore, G.D., Pan, D., Olds-Clarke, P. and Kopf, G.S. (1995) Development, 121, 1129-1137) we demonstrated that the tyrosine phosphorylation of a subset of mouse sperm proteins of M(r) 40,000-120,000 was correlated with the capacitation state of the sperm. The mechanism by which protein tyrosine phosphorylation is regulated in sperm during this process is the subject of this report. Cauda epididymal sperm, when incubated in media devoid of NaHCO3, CaCl2 or bovine serum albumin do not display the capacitation-associated increases in protein tyrosine phosphorylation of this subset of proteins. This NaHCO3, CaCl2 or bovine serum albumin requirement for protein tyrosine phosphorylation can be completely overcome by the addition of biologically active, but not inactive, cAMP analogues. Addition of the active cAMP analogues to sperm incubated in media devoid of NaHCO3, CaCl2 or bovine serum albumin overcomes the inability of these media to support capacitation, as assessed by the ability of the cells to acquire the pattern B chlortetracycline fluorescence, to undergo the zona pellucida-induced acrosome reaction and, in some cases, to fertilize metaphase II-arrested eggs in vitro. The effects of the cAMP analogues to enhance protein tyrosine phosphorylation and to promote capacitation appears to be at the level of the cAMP-dependent protein kinase (PKA), since two specific inhibitors of this enzyme (H-89 and Rp-cAMPS) block the capacitation-dependent increases in protein tyrosine phosphorylation in sperm incubated in media supporting capacitation. Capacitation, as assessed by the aforementioned endpoints, also appears to be inhibited by H-89 in a concentration-dependent manner. These results provide further evidence for the interrelationship between protein tyrosine phosphorylation and the appearance of the capacitated state in mouse sperm. They also demonstrate that both protein tyrosine phosphorylation and capacitation appear to be regulated by cAMP/PKA. Up-regulation of protein tyrosine phosphorylation by cAMP/PKA in sperm is, to our knowledge, the first demonstration of such an interrelationship between tyrosine kinase/phosphatase and PKA signaling pathways.
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PMID:Capacitation of mouse spermatozoa. II. Protein tyrosine phosphorylation and capacitation are regulated by a cAMP-dependent pathway. 753 69

The regulatory pathways involved in the ATP-stimulated Cl- secretion across rat epididymal epithelium were investigated by the short-circuit current (ISC) technique. Biphasic characteristic was observed in the ISC responded to ATP (0.01-10 microM). Inhibitor of P1 receptor, 8-phenyltheophylline (up to 100 microM), did not have any effect on both phases of the ATP-stimulated ISC. The order of potency for stimulation of the two phases in ISC was ATP > ADP >> AMP, adenosine, consistent with the presence of P2-purinoceptors. Cl- channel blocker, disulfonic acid stilbene (DIDS, 300 microM), only inhibited the first peak of the ATP-stimulated ISC while diphenylamine-dicarboxylic acid (DPC, 1 mM) reduced both, indicating the involvement of different conductance pathways. DIDS was found to have an inhibitory effect on Ca(2+)-activated ISC (induced by ionomycin, 10 microM) but not cAMP-activated ISC (induced by forskolin, 1 microM) which could only be blocked by DPC. Both peaks of the ATP-activated ISC could be significantly inhibited by pretreatment with a Ca(2+)-chelating agent, BAPTA-AM (50 microM). An increase in cellular cAMP content upon stimulation of ATP was measured by radioimmunoassay. No significant increase in cAMP production was observed in cells stimulated with adenosine. The ATP-induced cAMP increase was prevented by pretreatment with BAPTA-AM (100 microM) indicating that cAMP production upon ATP stimulation was secondary to an increase in intracellular Ca2+ concentration. These results indicate that the ATP-stimulated Cl- secretion could be mediated by Ca2+ and cAMP-dependent regulatory pathways giving rise to the biphasic nature of the ATP-induced ISC.
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PMID:Different regulatory pathways involved in ATP-stimulated chloride secretion in rat epididymal epithelium. 762 76

The influence of androgenic status on basal and stimulated cAMP production, adenylyl cyclase activities and immunoblot quantified GS alpha and Gi alpha 2 subunits of the adenylyl cyclase regulatory proteins were compared in confluent preadipocytes from subcutaneous (SC) and deep-intraabdominal (epididymal) fat deposits. Maximal cAMP response to isoproterenol was lower in SC than in epididymal preadipocytes. After castration, this site-specific difference was suppressed. cAMP response to 2-chloroadenosine, which was identical in the two types of preadipocytes, was decreased by castration in epididymal cells but not in SC cells. The catalytic activity of adenylyl cyclase and its maximal response to GTP were higher in epididymal than in SC preadipocytes. This response to GTP was decreased by castration in epididymal preadipocytes while it remained unchanged in SC preadipocytes. The catalytic activity of adenylyl cyclase was unchanged by androgenic status whatever the cell localization. Levels of GS alpha quantified by immunoblotting were not modified whatever the androgenic status and cell origin. Levels of Gi alpha 2 were not affected by the androgenic status as well, but were lower in SC than in epididymal cells. This study shows that components of the adenylyl cyclase system in preadipocytes are differently regulated by the androgenic status depending on the anatomical origin of the cells.
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PMID:Rat preadipocyte adenylyl cyclase: influence of fat localization and androgenic status. 780 12

A protein kinase that causes phosphorylation of serine and threonine residues of casein has been partially purified from goat cauda-epididymal sperm plasma membrane and characterized. The kinase, solubilized from the membrane with 1.0% Triton X-100, was purified to 480-fold by using DEAE-cellulose and casein-Sepharose affinity chromatographic techniques. The kinase is a strongly basic protein with pI of 9.5. The enzyme has a molecular mass of 310 kilodaltons as estimated by Sephacryl S-300 gel exclusion. The kinase showed affinity for protein substrates in the order membrane proteins > casein > phosvitin > histone > protamine. The apparent Km values of the kinase for casein and membrane proteins were 1 and 0.15 mg/mL, respectively. The synthetic peptides Kemptide and poly(Glu80Tyr20) did not serve as substrates of the enzyme. ATP, rather than GTP or PP(i), is the donor of phosphate for the phosphorylation reaction. Cyclic AMP and GMP, NaCl (0.25 M), KCl (0.25 M), Ca2+, calmodulin, phosphatidylserine, and muscle protein kinase inhibitor had no appreciable effect on the kinase activity. Heparin (0.5 microgram/mL) showed high affinity for inhibiting only 40% of the kinase activity, whereas polyamines at a relatively high concentration (5 mM) inhibited 40-50% of the enzymic activity. The kinase appears to be distinct from other protein kinases including casein kinases. The activity of the kinase derived from the purified sperm plasma membrane was markedly (approximately 90%) lost when the intact spermatozoa were pretreated with diazonium salt of sulfanilic acid, a membrane nonpenetrating surface probe.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Purification and characterization of a protein kinase from goat sperm plasma membrane. 784 Sep 41

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