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

Studies were carried out with rat epididymal fat pads first to compare the effects of the synthetic N-terminal 1-34 peptide of bovine parathyroid hormone and of the native hormone to determine whether this portion of the molecule is responsible for the lipolytic action of the hormone and second to determine whether this biologic action of parathyroid hormone is mediated by cyclic adenosine 3',5'-monophosphate. The N-terminal polypeptide was as effective as the native hormone in stimulating lipolysis in the concentration range between 10(-8) M and 10(-6) M. Parathyroid hormone stimulated lipolysis by isolated fat cells. The concentration of cyclic adenosine 3',5'-monophosphate in the fat pads was significantly increased by the hormone (10(-6)M). Lipolytic stimulation by parathyroid hormone (10(-6)M) was diminished by insulin (100 muU/ml) and prostaglandin E1 (1 mug/ml), both of which are known inhibitors of lipolysis. The findings indicate that the amino-terminal 1-34 peptide portion of parathyroid hormone is responsible for the lipolytic action and that this effect is mediated through cyclic adenosine 3',5'-monophosphate.
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PMID:Demonstration that cyclic adenosine 3',5'-monophosphate mediates the lipolytic action of parathyroid hormone. 18 4

Glycerol release from epididymal fat fragments of young adult (3-month old) ob/ob mice was three times lower than normal, on a tissue weight basis. Dose-response curves in response to isoproterenol and ACTH-(1--24) indicated that the capacity of the lipolytic process was reduced. However, the sensitivity to both hormones was normal, i.e. greater for ACTH than for isoproterenol. The burst of cyclic AMP observed at 7 minutes was affected even more than the lipolytic capacity in adipose tissue from obese mice. This was already observed in 1-month old animals, i.e. at a time when total body weight was still normal. It is concluded that the adenylate cyclase system is defective in adipose tissue of ob/ob mice. Besides, glucagon, vasoactive intestinal polypeptide, and secretin failed to stimulate glycerol release and cyclic AMP accumulation in both ob/ob, ob+/ob+, and HA-ICR mice, suggesting that mouse adipose tissue does not possess receptors for this group of hormones.
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PMID:Lipolysis and cyclic AMP levels in epididymal adipose tissue of obese-hyperglycaemic mice. 20 30

Specific modification of the single lysine residue (Lys-12) in glucagon with O-methylisourea has been effected by blocking the reactivity of the amino terminal histidine with copper, providing a method for obtaining [12-homoarginine]glucagon. It was found that as a side reaction, under the conditions of the modification reaction, Cu(II) catalyzed cleavage of the polypeptide chain between Asp-9 and Tyr-10, and between Lys-12 and Tyr-13. This observation may be of value for development of a sequence-specific peptide cleavage procedure. The dilute solution conformations of glucagon and [12-homoarginine]-glucagon were compared by circular dichroism, fluorescence, phosphorescence, energy transfer, and optical detection of magnetic resonance. The results indicate that conversion of Lys-12 to homoarginine does not alter the helix content the side chain conformation in the vicinity of the tyrosine and tryptophan residues, or the relative distances and orientations between these residues. However, the modification reduces the hormone potency towards activation of lipolysis in isolated rat epididymal fat cells by a factor of seven. We attribute the loss of potency to an interference with a specific interaction between the lysine residue and the fat cell hormone receptor, and not to a change in the solution conformation of the hormone.
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PMID:[12-Homoarginine]glucagon: synthesis and observations on conformation, biological activity, and copper-mediated peptide cleavage. 42 94

The effects of trypsin inhibitors and phospholipase inhibitors on the acrosome reaction of washed cauda epididymal sperm of golden hamsters were studied using two different incubation systems. One incubation system, a non-synchronous acrosome reaction inducing system, included the use of a highly purified BSA and a protein-free motility factor preparation from hamster adrenal gland. The other system was a relatively synchronous acrosome reaction-inducing-system utilizing the calcium ionophore A23187. Acrosome reactions were inhibited by three low molecular weight synthetic trypsin inhibitors, benzamidine, NPGB and TLCK, when they were added five minutes prior to the initial occurrence of acrosome reactions in the non-synchronous system or five minutes prior to induction of acrosome reactions by A23187 in the synchronous system. Two phospholipase A inhibitors, p-bromophenacyl bromide and mepacrine, were also effective in inhibiting hamster sperm acrosome reactions in both incubation systems. TPCK, an inhibitor of several non-trypsin-like proteases, indomethacin, a prostaglandin synthetase inhibitor, and soybean trypsin inhibitor, a large molecular weight polypeptide, did not inhibit acrosome reactions. The inhibition of those acrosome reactions induced by A23187 provides further indirect evidence that the effective inhibitors were functioning at a site within the sperm. The overall results provide: (1) further support for our earlier work suggesting the involvement of an internal trypsin-like enzyme (presumably acrosin) rather than an exogenous trypsin-like enzyme in the hamster sperm acrosome reaction and (2) the first evidence suggesting the possibility that a sperm phospholipase may also be involved in the mammalian acrosome reaction.
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PMID:Further evidence in support of a role for hamster sperm hydrolytic enzymes in the acrosome reaction. 57 94

The perforatorium of rat spermatozoa was isolated and its protein composition determined. SDS-polyacrylamide gel electrophoresis showed that the organelle is composed of a single polypeptide component with a molecular weight of 13,000. The perforatorium becomes more resistant to solubilization during epididymal transit due to an apparent increase in disulphide bond content. Amino acid analysis of the perforatorium polypeptide revealed a content of 6-5% cysteine.
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PMID:Isolation and characterization of the perforatorium of rat spermatozoa. 95 29

Monoclonal antibodies directed against four different polypeptide epitopes on the Mr approximately 94,000 steroid-binding subunit of the rat liver cytosolic glucocorticoid receptor (GcR) were used to probe Western blots of epididymal spermatozoa from rats and mice. Two sperm polypeptides with apparent molecular weights of 94,000 (indistinguishable in size from the liver GcR subunit) and 150,000 reacted with these antibodies. Other polypeptides that are present in a wide variety of somatic cells [lamin-A, -B, and -C; topoisomerase-I; poly(ADP-ribose) polymerase; the 62-kilodalton internal nuclear matrix protein; the nucleolar protein B23; and histone H1] could not be detected in these preparations of spermatozoa, thus appearing to rule out contamination by somatic cells. Rat and mouse pachytene spermatocytes and round spermatids contained much lower amounts of the Mr approximately 94,000 and 150,000 polypeptides. These results suggested that the steroid-binding subunit of the GcR might be accumulated late in spermatogenesis. Consistent with this view, a 6-kilobase mRNA (identical in size to a mRNA detected in mouse somatic cell lines) was detected when Northern blots of mouse round spermatid RNA were probed with a cDNA to the steroid-binding GcR subunit. Although the results described above suggest the presence of GcR in rodent sperm, high affinity binding of glucocorticoids to epididymal sperm could not be detected in a whole cell binding assay. Further analysis revealed that the Mr approximately 90,000 heat shock protein (hsp90), a component reportedly required for high affinity ligand binding to the GcR, was present in early germ cells, but absent from rodent epididymal sperm. These results suggest that the Mr approximately 94,000 steroid-binding subunit of the GcR and an immunologically related Mr approximately 150,000 polypeptide are specifically accumulated during the later stages of rodent spermatogenesis, but are not assembled into receptor complexes capable of binding steroid. In addition, these results support the view that hsp90 is required for high affinity binding of glucocorticoids to the Mr approximately 94,000 GcR subunit in intact cells.
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PMID:Evidence that rodent epididymal sperm contain the Mr approximately 94,000 glucocorticoid receptor but lack the Mr approximately 90,000 heat shock protein. 157 14

The amino acid sequence of a major human epididymis-specific protein was deduced from the nucleotide sequence of its cloned cDNA. The encoded product showed characteristics of a secretory protein, with a signal peptide followed by a small (approximately 10-kDa), acidic (pI 4.3), and cysteine-rich polypeptide. The positions of half-cysteines suggested that it was a two-domain member of the family of 'four-disulfide core' proteins to which a number of proteinase inhibitors belong. Southern blot analyses of human genomic DNA showed that the transcripts originated from a single copy gene. Northern blot and in situ transcript hybridization specifically localized the HE4 (human epididymis gene product) mRNA to the epithelial cells of the epididymal duct, predominantly within the distal sections. A possible function in sperm maturation as indicated by amino acid similarities to extracellular proteinase inhibitors of genital tract mucous secretions is discussed in the context of its tissue-specific transcription.
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PMID:A major human epididymis-specific cDNA encodes a protein with sequence homology to extracellular proteinase inhibitors. 168 87

Experiments have been carried out characterizing an Mr 22,000 protein present in the acrosomes of hamster and bull spermatozoa. The Mr 22,000 protein is resistant to solubilization in detergent solutions containing high or low salt and has a pI of -5.2. With various lectins, the protein from hamster sperm was shown to be sparingly glycosylated with N-acetylglucosamine, mannose, and galactose while that from the bull demonstrated a slight reactivity for galactose. Using a specific monoclonal antibody (MAB 4/18), the Mr 22,000 polypeptide has been localized exclusively to the acrosomes of mature testicular and epididymal hamster and bovine sperm. Acrosomal components of differentiating bovine and hamster spermatids in tissue sections did not react with the monoclonal antibody, although the protein was present in immunoblots of round spermatids. In bovine sperm, MAB 4/18-staining at the ultrastructural level with immunogold-labeled second antibody was present as a reticulum throughout the acrosomal cap and as punctate aggregates in the equatorial segment. In hamster sperm, MAB 4/18-reactivity was present along the periphery of the acrosome in conjunction with matrix components (M1 and M2), as well as along the inner acrosomal membrane. These observations indicate that the acrosomes of bovine and hamster sperm possess an immunologically related Mr 22,000 protein and suggest that differences in MAB 4/18-staining of spermatids and spermatozoa is a result of epitope modification and/or a change in accessibility of the epitope to the antibody probe during the course of spermiogenesis. Based on its localization and solubility properties, we suggest that the Mr 22,000 protein, in conjunction with other polypeptides, forms a structural framework to maintain acrosomal shape and/or compartmentalize acrosomal contents.
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PMID:Characterization of an acrosomal matrix protein in hamster and bovine spermatids and spermatozoa. 169 46

Polyclonal antisera raised against polypeptide components of two rat Sertoli cell secretory proteins, designated protein S70 and S45-S35 heterodimeric protein on the basis of cell origin and estimated molecular weight, were used to identify antigenic sites in 1) rat testis, 2) cultured Sertoli cells, 3) developing spermatids (collected from spermatogenic stage-specific seminiferous tubular segments), and 4) epididymal sperm. Indirect immunofluorescence, immunoperoxidase, and immunogold electron microscopy (single and double labeling) were used. Immunocytochemical techniques have detected antigenic sites in 1) the cytoplasm of Sertoli cells in the intact seminiferous tubule and in culture in the form of a punctuate, granular-like pattern, and 2) the acrosome (but not the Golgi region) and tail of developing spermatids and sperm. In developing spermatids, the principal piece of the tail displays a characteristic apical-to-distal immunoreactive banding pattern that correlates both temporally and spatially with the reported multistep assembly of outer dense fibers along the axoneme. The immunoreactivity of the acrosome, connecting piece, and outer dense fibers of the sperm tail was confirmed by immunogold electron microscopy. A precise identification of the component(s) of the outer dense fiber region responsible for the antigenic homology with Sertoli cell secretory proteins is under investigation.
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PMID:Immunogold electron microscopic localization of antigenic sites in the outer dense fiber region of rat sperm tail obtained by using antisera to two Sertoli cell secretory proteins. 172 Oct 88

We had identified earlier a germ cell-specific lamin of 60 kDa in rat which is related to somatic lamin B. This polypeptide was shown to be the only major component organizing the lamina structure of round spermatids. In the present study, we find that this 60-kDa polypeptide persists in the testicular and epididymal sperms of rat. We also show, by indirect immunofluorescence studies, that the 60-kDa protein is antigenically conserved in the germ cells of grasshopper, rooster, and frog and in plant meiocytes. The distribution of fluorescence among the various germ cell populations shows that the antigen is located around the nuclear cortex of pre- and postmeiotic germ cells, while it is distributed all over the pachytene nuclei. The anti-60-kDa polyclonal antibodies also reacted with a 60-kDa polypeptide in the Western blot analysis of nuclear matrix proteins of grasshopper germ cells. The similar fluorescent localization pattern of the antigen observed in various eukaryotic species strongly suggests that this germ cell-specific lamin may play a very crucial role during meiotic prophase, particularly during homologous chromosome pairing and recombination.
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PMID:Evolutionary conservation of a germ cell-specific lamin persisting through mammalian spermiogenesis. 172 60


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