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

Acidic epididymal glycoprotein (AEG) had a slight stimulatory effect on the motility of spermatozoa showing low initial motility which had been removed by micropuncture from the caput and corpus epididymidis of rats. However, similar effects were seen when bovine serum albumin (BSA) or purified gammaglobulin against AEG was used instead of AEG. Furthermore, BSA, normal rabbit serum and serum from a rabbit immunized against AEG reduced the motility of spermatozoa which showed high initial motility after removal from the caput, while AEG had no effect. These studies emphasize the importance of the effects of proteins on the motility of spermatozoa but do not provide any clear evidence for a specific effect of AEG.
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PMID:The effects of acidic epididymal glycoprotein (AEG) and some other proteins on the motility of rat epididymal spermatozoa. 619 70

A glycoprotein of molecular weight 32K has been isolated and purified from the rat caudal epididymal fluid by gel filtration, ion-exchange and affinity chromatography. The highly purified protein was labeled with radioactive iodine and the binding of the 125I-labeled 32K rat epididymal protein (REP) to washed rat caudal epididymal sperm was studied under various conditions. Scatchard plots of the binding data revealed two binding kinetics. One bound with high affinity (KD = 2.6 X 10(-10) ) but low capacity. The other bound with lower affinity (KD = 2.2 X 10(-9)M) but high capacity. The rate of binding of the labeled protein to sperm was dependent on the temperature of the incubation medium. At the scrotal temperature of 33 degrees C, maximal binding was obtained after 40 min. However, at 22 degrees C equilibrium state was reached after 90 min and at 0 degrees C, the equilibrium rate was not reached even after 120 min of incubation. Binding showed dependence on extracellular pH (optimal pH at 4) and ionic strength of the incubation medium. High ionic strength was found to inhibit binding of the 125I-labeled 32K REP to rat caudal epididymal sperm. Specific binding was abolished by 100-fold molar excess unlabeled 32K REP or by native rat caudal epididymal fluid proteins, but not by albumin or ovalbumin. This indicates high specificity of binding. This study has provided direct evidence for the interaction of an epididymal protein with epididymal spermatozoa.
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PMID:Studies on the binding of a 32K rat epididymal protein to rat epididymal spermatozoa. 629 30

Glycoproteins on the plasma membrane of testicular and cauda epididymidal spermatozoa have been labeled with galactose oxidase/NaB [3H]4 and sodium metaperiodate/NaB[3H]4, followed by analysis on SDS polyacrylamide gels. The major glycoprotein labeling on testicular spermatozoa has a molecular weight 110,000 whereas on cauda epididymidal spermatozoa greater than 90% of the radio-label is incorporated into proteins of molecular weight 32,000. These 32,000-mol wt X proteins are homologous with proteins of similar molecular weight purified from the epididymal secretion and which have been shown previously to be synthesized in the caput epididymidis under hormonal control. Immunofluorescence revealed that the 32,000-mol wt proteins are present on the flagellum of mature but not immature spermatozoa and that they have a patchy distribution suggesting that they are mobile within the plane of the membrane. The membrane-bound 32,000-mol wt proteins possess hydrophobic domains as revealed by charge-shift electrophoresis and they also label with a lipophilic photoaffinity probe suggesting that they are in contact with the lipid bilayer. The evidence indicates that there is a considerable reorganization of the molecular structure of the plasma membrane of spermatozoa during maturation in the epididymis and that some of the changes are brought about by a direct interaction with epididymal secretory proteins.
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PMID:Changes in plasma membrane glycoproteins of rat spermatozoa during maturation in the epididymis. 629 50

We report here the purification, partial characterization and immunofluorescent localization of a dimeric acidic glycoprotein (DAG-protein) secreted by cultures of Sertoli cells of rat testes. Partially purified protein was obtained after chromatography over Sepharose 4B under conditions which favored a soluble, nonaggregated form of the protein. Rechromatography over the same column under reducing conditions yielded very pure monomers of 41,000 daltons and 29,000 daltons. Antibodies were prepared against the mixed monomers and used to immunoprecipitate proteins in spent medium from cultures incubated with [35S] methionine, 35SO4 = or tunicamycin. DAG-protein and another protein (Band 4, 70,000 daltons) were coprecipitated by the antiserum and all contained 35SO4 = in their structures. It was shown by Western blotting that the antiserum cross-reacted very weakly with Band 4 protein. The DAG-protein polypeptides secreted in the presence of tunicamycin were assumed to lack N-glycosylation and exhibited apparent molecular weights of 27,000 and 21,000 daltons. Immunoprecipitations of media from organ cultures of testis and epididymis yielded DAG-protein of slightly lower molecular weight than the protein secreted in Sertoli cell cultures. Indirect immunofluorescence of DAG-protein in paraffin sections of testis and epididymis revealed that the protein was concentrated in the cytoplasm of Sertoli cells, on the stereocilia of epididymal principal cells, in the cytoplasm of epididymal halo cells, and was associated with late spermatids and mature sperm. Sperm were specifically labeled on the acrosome, at the neck, and on the endpiece of the tail. No enzymatic or structural function has been ascribed to DAG-protein as yet, but the protein must play a pivotal role in spermatogenesis because it is secreted by both the testis and epididymis and becomes an integral component of sperm.
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PMID:A sulfated glycoprotein synthesized by Sertoli cells and by epididymal cells is a component of the sperm membrane. 639 59

The localization of glycoprotein synthesis and storage was studied during acrosome formation in guinea-pig using fine-structure autoradiography after (3H)-fucose incorporation. Three days after (3H)-fucose injection, labelling in spermatids was concentrated in the matrix of developing acrosomes, and it was evident that the fucosylation of acrosomal glycoproteins largely overshadowed the fucosylation of other spermatid glycoproteins. Acrosin labelling and its quantitative relation to labelling of other glycoproteins was examined in mature rabbit spermatozoa after incorporation of (14C)-fucose or (14C)-glucosamine during spermatogenesis. Cauda epididymis spermatozoa recovered 21 days after intratesticular application of (14C)-fucose or (14C)-glucosamine were analysed for acrosin specific labelling after acid extraction and gel filtration. In all the material examined, radioactivity was detected in the proacrosine fractions; radioactivity in purified proacrosin amounted to at least 2% of the total radioactivity in the epididymal sperm population. In addition to the peak with radioactive proacrosin, another radioactive peak in (14C)-glucosamine-labelled material was attributed to a glycoprotein intraacrosomal inhibitor of acrosin. It is concluded that (pro)acrosin (acrosin-inhibitor) complexes seem to contribute significantly to acrosomal glycoprotein labelling by radioactive sugars and that the distribution of these complexes may at least correspond to their cytochemically detectable component, acrosin. The superposition of the distribution of acrosin and of other acrosomal glycoproteins during acrosome reaction can be explained by the fact that the dispersal of most of the acrosomal content is linked to proacrosin activation.
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PMID:Studies on acrosome labelling of mammalian spermatozoa by radioactive sugars. 643 21

The three main segments of the elephant epididymis were examined for the occurrence, in the spermatozoa and lining epithelium, of carbohydrates, neutral lipids and phospholipids, ATPase, alkaline phosphatase, succinic dehydrogenase, glucose-6-phosphate dehydrogenase, diaphorases, hydroxysteroid dehydrogenases, acid phosphatase and non-specific esterase. The most distinct feature of the carbohydrate content of the epididymis was a layer of acidic, alcian blue-positive glycoprotein over the luminal surface of the epithelium, particularly in the terminal segment. PAS-positive, diastase-resistant inclusions were also found throughout the epdidymis. Neutral lipid occurred as droplets above and below the nucleus in the epithelium of the middle segment, and as supranuclear accumulations in the terminal segment. All the enzymes except the steroid dehydrogenases were detected in the epididymal epithelium, and all except the steroid dehydrogenases and acid phosphatase were detected in the spermatozoa. There was considerable variation in the intensity of the cytochemical reactions in the epithelium, but not in the spermatozoa, in different regions of the epididymis. In general, the enzymes involved in active transport showed strongest reactions in the initial and terminal segments, the reactions in the stereocilia being the most intense. The enzymes involved in energy metabolism showed strongest reactions in the middle and terminal segments, with the activity being fairly evenly distributed throughout the cytoplasm of the principal cells. However, the two lysosomal enzymes which were studied showed quite different distributions: the reactions for acid phosphatase were strongest in the initial and middle segments, whilst the reactions for non-specific esterase were strongest in the middle and terminal segments. It is suggested that the initial segment is involved in absorptive and anabolic activity, the middle segment in anabolic activity, and the terminal segment (where spermatozoa are stored ready for ejaculation) in considerable metabolic activity and active transport of substrates across the epithelium.
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PMID:Studies of the deferent ducts from the testis of the African elephant, Loxodonta africana. II. Histochemistry of the epididymis. 644 36

In many mammals, sperm are immotile while stored in the caudal epididymis and do not become motile until ejaculation. We report here our investigation of the mechanism that initiates motility in mature rat epididymal sperm. We found that an external "activator" is not required to initiate rat sperm motility since immotile sperm started to swim immediately when exposed to solutions that contributed only osmotic support. Instead, we found that epididymal rat sperm are kept fully immobilized by a high molecular weight glycoprotein, "immobilin," that we have isolated from rat cauda epididymal (CE) fluid. Our results strongly support the hypothesis that immobilin inhibits sperm motility mechanically simply by creating a highly viscoelastic environment: 1) rat CE fluid inhibited the motility of such disparate cells as rat sperm, E. coli. and rabbit sperm (which are fully motile in rabbit CE fluid), 2) the degree to which a variety of enzymatic treatments or slight dilution of the CE fluid initiated sperm motility depended only on the degree to which the treatment reduced the viscoelastic drag of the fluid, and 3) centrifugation of CE fluid simultaneously copurified the component of the fluid that immobilizes the sperm, the component that renders the fluid viscoelastic, and the glycoprotein immobilin.
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PMID:Rat sperm are mechanically immobilized in the caudal epididymis by "immobilin," a high molecular weight glycoprotein. 665 88

3H-sialyl residues transfer by subcellular epididymal fractions [plasma membrane (PM), microsomes (MI), and mitochondria (MT)] to both endogenous and exogenous acceptors was studied. Their fraction purity was valued (5' nucleotidase and glucose 6-phosphatase activities). The glycoprotein or glycolipid N-acetyl neuraminyl transferase activity in microsomes were 5 times higher in caput than in cauda (624 to 125 pmoles/30 min/mg protein). PM activity also was higher in caput. In MT fraction, the activity was smaller. Two mechanisms related to spermatozoa glycoprotein changes during maturation are proposed: secretion to the lumen of molecules previously glycosilated in microsomes and transialylation to spermatozoa from membranal ectoenzymes localized on the surface of the epididymal epithelium.
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PMID:Microsomal and plasma membrane sialyltransferase activity in rat epididymis. 668 2

A Mr = 32,000 membrane glycoprotein can be uniquely labeled by galactose oxidase/[3H]sodium borohydride on rat caudal, but not caput, epididymal sperm. It has been suggested that this protein is related to a Mr = 32,000 galactose oxidase-sensitive glycoprotein present in rat caudal epididymal fluid. The tritiated membrane glycoprotein was solubilized and its hydrodynamic properties were determined by conventional gel filtration, high performance gel filtration, sedimentation rate determination in linear sucrose gradients prepared in H2O and D2O, and equilibrium isopycnic centrifugations in CsCl. The Stokes radius and sedimentation coefficient were 4.87 +/- 0.07 nm and 1.73 +/- 0.08 S, respectively. The sedimentation profile in CsCl gradients was asymmetric with a major peak occurring at a density of 1.081 g/cm3 (v = 0.92 cm3/g) and a shoulder at 1.108 g/cm3 (v = 0.90 cm3/g). The glycoprotein did not enter a 5 to 20% linear sucrose gradient prepared in D2O and could be extracted from the intact sperm into acidic chloroform:methanol solutions. These data are consistent with a protein which binds substantial amounts of detergent and/or lipid and has exposed hydrophobic regions. Two-dimensional gel electrophoresis indicated that the membrane protein exhibits charge heterogeneity, with the major components having pI values of 5.4 and 4.9. The fluid glycoprotein was monodisperse on two-dimensional gel electrophoresis having a pI of 3.8. Binding studies failed to demonstrate specific binding of the Mr = 32,000 caudal fluid glycoprotein to caput cells. Moreover, "Western blots" of electrophoretically resolved caput and caudal fluid proteins, followed by immunolabeling with antibodies raised against unfractionated caudal fluid, demonstrated the presence of a Mr = 32,000 protein in caudal fluid which was absent from caput epididymal fluid. Using the same technique, it was shown that antibodies raised against caudal fluid proteins did not cross-react with a Mr = 32,000 caudal membrane glycoprotein. Our data do not support the view that the Mr = 32,000 fluid and membrane proteins are identical.
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PMID:Characterization of a maturation-associated glycoprotein on the plasma membrane of rat caudal epididymal sperm. 669 99

Mouse and guinea pig epididymal tissues have been investigated by light and electron microscopic autoradiography after long intervals ranging from 24 h to 5 days postinjection (p.i.) of the glycoprotein precursors, L-fucose-6-3H or D-glucosamine-1-3H. Using modified fixations to enhance glycoprotein preservation in situ, we found intense labelling of luminal contents in at least some of the epididymal segments after all the intervals investigated. At 24 h p.i., the label in guinea pig was associated with spermatozoa during remodelling of the acrosome in segment II, and at 3 days p.i., radioactivity was trapped within sperm head associations ("rouleaux") in segment IV of the epididymis. At this time, similar rouleau labelling extended from segment IV to segment VIII. In mouse, the luminal contents of the cauda epididymis were still intensely labelled at 5 days p.i.; analysis of the electron microscopic autoradiograms showed that relative grain concentration over the spermatozoa was twice that of the epididymal plasma. This concentration was especially elevated in the region of the sperm head. These findings taken together were interpreted as the binding of secreted epididymal glycoproteins to spermatozoa during sperm transit through the epididymis. In contrast to luminal contents, the labelling of the epididymal epithelium was generally lower, except on the clear cells which showed more pronounced labelling than the neighboring principal cells in mouse cauda epididymis at 5 days p.i. This label probably originated from the resorption of luminal glycoproteins.
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PMID:Binding of secreted glycoproteins to spermatozoa in the mammalian epididymis: a fine-structure autoradiographic study. 670 37


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