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

Impact of altered serum prolactin status on enzymes involved in glycoprotein metabolism in epididymal tissue of matured monkeys was studied. Hyperprolactinemia (ovine prolactin-250 micrograms/kg body weight/day for 30 days) significantly inhibited the specific activities of dolichylphosphate mannosyl transferase, dolichylphosphate glucosyl transferase and galactosyl transferase, in the epididymal tissues. However, it had an enhanced effect on epididymal glycosidases such as beta-galactosidase, beta-N-acetyl glucosaminidase, beta-N-acetyl galactosaminidase, alpha-mannosidase and alpha-L-fucosidase. Hypoprolactinemia (bromocriptine mesylate-1-mg/kg body weight/day for 30 days) on other hand had no significant effect on the specific activities of both, glycosyltransferases and glycosidases, in the epididymal tissues. The results suggest that hyperprolactinemia inhibits epididymal glycoprotein metabolism by impairing the incorporation of oligosaccharide units into proteins with enhanced degradation. This may have adverse effect on events leading to sperm maturation in epididymal environment.
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PMID:Role of prolactin on epididymal glycoprotein metabolism in matured monkeys, Macaca radiata: specific activities of glycosyltransferases and glycosidases. 129 32

The bovine seminal plasma is formed mainly by secretions of epididymis and the glandular epithelia in ampulla, seminal vesicles, prostate and Cowper's glands. The contribution of each organ to the hydrolytic enzyme activities (glycosidases, exopeptidases, phospholipases) of the bull seminal plasma has been analyzed and is reviewed in this paper with special emphasis on the role of the accessory glands. Seminal vesicles seem to have a major role in the secretion of seminal plasma acid alpha-glucosidase, acid alpha-mannosidase and beta-N-acetylhexosaminidase, aminopeptidase A, dipeptidyl peptidase II and IV and gamma-glutamyl transpeptidase as well as Ca(2+)-dependent and Ca(2+)-independent phospholipases A2 with distinct substrate specificities, a choline-specific phospholipase C and a Co2+ (Mn2+)-activated sphingomyelinase. The enzyme pattern in the ampulla closely resembled that of the seminal vesicles and obviously contributes to the seminal plasma level of these hydrolases. The bull prostate and Cowper's glands contained a strong Ca(2+)-dependent phospholipase A2 activity. However, these glands may not contribute to the seminal plasma PLA2 activity. At ejaculation the epididymal spermatozoa are exposed to these enzymes. They may have a specific affinity to sugar, peptide or phospholipid residues at distinct sites of the sperm surface. These enzymes may also participate in the digestion of various other semen components to create a suitable milieu for the emitted spermatozoa.
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PMID:Hydrolases from bovine seminal vesicle, prostate and Cowper's gland. 213 63

Mannostatin A is a metabolite produced by the microorganism Streptoverticillium verticillus and reported to be a potent competitive inhibitor of rat epididymal alpha-mannosidase. When tested against a number of other arylglycosidases, mannostatin A was inactive toward alpha- and beta-glucosidase and galactosidase as well as beta-mannosidase, but it was a potent inhibitor of jack bean, mung bean, and rat liver lysosomal alpha-mannosidases, with estimated IC50's of 70 nM, 450 nM, and 160 nM, respectively. The type of inhibition was competitive in nature. This compound also proved to be an effective competitive inhibitor of the glycoprotein-processing enzyme mannosidase II (IC50 of about 10-15 nM with p-nitrophenyl alpha-D-mannopyranoside as substrate, and about 90 nM with [3H]mannose-labeled GlcNAc-Man5GlcNAc as substrate). However, it was virtually inactive toward mannosidase I. The N-acetylated derivative of mannostatin A had no inhibitory activity. In cell culture studies, mannostatin A also proved to be a potent inhibitor of glycoprotein processing. Thus, in influenza virus infected Madin Darby canine kidney (MDCK) cells, mannostatin A blocked the normal formation of complex types of oligosaccharides on the viral glycoproteins and caused the accumulation of hybrid types of oligosaccharides. This observation is in keeping with other data which indicate that the site of action of mannostatin A is mannosidase II. Thus, mannostatin A represents the first nonalkaloidal processing inhibitor and adds to the growing list of chemical structures that can have important biological activity.
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PMID:Mannostatin A, a new glycoprotein-processing inhibitor. 227 38

Seven glycosidases (beta-N-acetylglucosaminidase, alpha-fucosidase, beta-galactosidase, acid alpha-glucosidase, beta-glucuronidase, acid and neutral alpha-mannosidase) were analysed in seminal plasma from the first and second successive ejaculates in normal Ayrshire bulls. In comparison to our previous data the results indicate that beta-N-acetylglucosaminidase, beta-galactosidase and beta-glucuronidase are derived mainly from epididymal secretions, while alpha-fucosidase and particularly neutral alpha-mannosidase originate additionally from the spermatozoan cytoplasmic droplets. The seminal vesicles appear to contribute particularly to the seminal plasma acid alpha-glucosidase and acid alpha-mannosidase activities. The seminal plasma enzymes derived from the epididymis and cytoplasmic droplets were suppressed in semen samples with low sperm density or with high numbers of abnormal spermatozoa. The epididymal and seminal vesicle enzymes could be utilized in assessment of the secretory/functional capacity of these glands.
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PMID:Comparison of glycosidase levels in bovine seminal plasma. 311 30

Acid and neutral alpha-mannosidase activities were studied in the bull reproductive tissues, isolated spermatozoa, epididymal and seminal vesicle secretion and seminal plasma. The acid enzyme in the seminal plasma mainly derived from the epididymal secretion, while the neutral one was enriched in the sperm cells. The latter activity in the seminal plasma appears to be due to an enzyme released from the cytoplasmic droplets in the epididymis. The acid enzyme had a molecular weight of 220,000-320,000, pI 7.3-6.0 and an optimum at pH 4.0. It was sensitive to swainsonine but was stimulated by Zn2+. The neutral enzyme had a molecular weight of 360,000-460,000, pI 5.4-4.7 and showed double optima at pH 5.5 and 6.0-7.0. It was resistant to swainsonine but was markedly activated by Co2+ or Fe2+. The neutral enzyme was also more sensitive to thermal inactivation than the acid one.
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PMID:Characterization of acid and neutral alpha-mannosidases in bull semen and reproductive organs. 359 78

A new aminosugar named nojirimycin B (1) has been isolated as its bisulfite adduct from the culture broth of Streptomyces lavendulae SF-425, together with nojirimycin. Microbiological oxidation of 1 with Gluconobacter suboxydans IAM 1829 gave a delta-lactam (2). The structures of 1 and 2 were determined to be 5-amino-5-deoxy-D-mannopyranose and D-mannonic-delta-lactam, respectively, on the basis of 1H NMR spectroscopy and X-ray structural analysis. Both 1 and 2 exhibited powerful inhibitory activity against rat epididymal alpha-mannosidase and apricot beta-glucosidase.
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PMID:Novel glycosidase inhibitors, nojirimycin B and D-mannonic-delta-lactam. Isolation, structure determination and biological property. 654 15

Three isoenzymic species of neutral alpha-mannosidase (I, II and III) were partially purified from rat epididymis and characterized. Calcium phosphate gel preferentially adsorbed acidic alpha-mannosidase activity, thereby removing the acidic enzyme from the neutral mannosidases. The neutral enzymes, which are of cytosolic origin, require Co2+ for activity, and Mn2+ can substitute partially for Co2+. Mg2+ or Ca2+ had little effect on the activity of the isoenzymes, whereas Zn2+ (100 microM) was a potent inhibitor of the mannosidases. The Km values of mannosidases I, II and III for Co2+ were 10, 10 and 2.7 mM respectively. There was marked alteration of the specific activity of the neutral alpha-mannosidases during epididymal development in vivo. The specific activities of mannosidases I and II were relatively high in the young (24 days) rats, and during the subsequent development the specific activities decreased markedly (approx. 2-3-fold). On the contrary, mannosidase III, which showed relatively low specific activity during 24-45 days of age, increased markedly (approx. 2-fold) as the animals reached adulthood.
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PMID:Enzymic characteristics of the isoenzymes of rat epididymal neutral alpha-mannosidases and their changes during development in vivo. 671 26

This study demonstrates that beta-glucuronidase from rat preputial glands binds with high affinity to spermatozoa from the cauda epididymis. The binding was calcium-independent and was inhibited by mannose-6-phosphate, but not by other phosphorylated or non-phosphorylated sugars. Binding was also inhibited by alpha-mannosidase from Dictyostelium discoideum, an enzyme known to have mannose-6-phosphate as the ligand. From solubilized sperm membranes, a protein of > 200 kDa and one of 45 kDa, were absorbed to a column of D. discoideum enzyme and to a phosphomannan column respectively, and eluted with mannose-6-phosphate. According to histochemical observations at the light and the electron microscopic level, gold particles coated with the enzyme became bound to the external surface of the plasmalemma in the acrosomal region of caudal spermatozoa. Similar labelling was observed using gold particles coated with antibodies against the rat 300 kDa phosphomannosyl receptor. The existence of phosphomannosyl receptors on the sperm plasma membrane, and our previous demonstration of the presence of affinity sites for epididymal beta-galactosidase on these gametes which is inhibited by phosphofructosyl derivatives, suggest strongly that maturing spermatozoa could be a target for glycosidases secreted into the lumen of the cauda epididymis, which then become bound to these cells via different ligand-receptor systems.
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PMID:Phosphomannosyl receptors on the surface of spermatozoa from the cauda epididymis of the rat. 755 73

The epithelium of caput and cauda epididymidis of the rat was studied with transmission electron microscopy (TEM) and freeze-fracture techniques. In thin sections of both zones, the tissue consisted mainly of tall columnar cells (principal cells) with long sterocilia. Clusters of small membrane-bound vesicles were located in the lumen between or immediately over the stereocilia. Freeze-fracture replicas also displayed groups of smooth-surface vesicles in the same location. Membrane-bound vesicles isolated from the lumen of the rat epididymis were studied by TEM. In thin sections, some of them contained an electron dense material and others looked empty. In addition, the hydrolases: beta-galactosidase, N-acetyl-glycosaminidase, alpha-mannosidase, aryl-sulfatase and beta-glucuronidase were detectable in pellets of vesicles treated with Triton X-100. The results presented here indicate the presence of membrane-bound vesicles observed by two different methodologies in the rat epididymal fluid and demonstrate five glycosidases in their content.
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PMID:Morphological and enzymatic study of membrane-bound vesicles from the lumen of the rat epididymis. 775 84

Activity of glycosidases in the epididymis was influenced by several factors originating in the testis. Activities of all the three glycosidases studied viz., beta-glucosidase, beta-galactosidase and alpha-mannosidase were found to be significantly lower in the epididymis of orchidectomized animals than in sham operated rats. However, an enhanced activity of epididymal beta-galactosidase and alpha-mannosidase was noticed in prolactin treated orchidectomized rats compared to orchidectomized rats given vehicle alone. On the other hand, activity of these two enzymes in bromocriptine treated orchidectomized rats was even lower than that found in orchidectomized rats given vehicle. Neither prolactin nor bromocriptine treatment had any significant influence on the epididymal beta-glucosidase. The results suggest a selective but definite action of prolactin on epididymal glycosidases.
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PMID:Modulation in activity of some epididymal glycosidases by prolactin. 835 47


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