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

The localization of immobilin, a glycoprotein known to be present and to immobilize spermatozoa in the lumen of the epididymis, was investigated using light and electron microscope immunocytochemistry. In the light microscope, a distinct immunoperoxidase reaction product was observed in the lumen over the brush border of the epithelial nonciliated cells of the efferent ducts, while only a faint reaction was seen over their supranuclear region. In the proximal area of the initial segment of the epididymis no immunoperoxidase staining was observed either over epithelial cells or in the lumen. In the middle area of the initial segment, several epithelial principal cells became intensely immunostained but the majority were unstained; a weak reaction appeared in the lumen. In the distal area of the initial segment, more principal cells became immunostained, and while some were intensely reactive, others were moderately or weakly stained or unreactive. In the intermediate zone and proximal caput epididymidis, the principal cells showed the maximal immunoreactivity with all principal cells being reactive; staining in the lumen also reached its maximal reactivity in these areas. Immunostaining of principal cells gradually decreased along the epididymal duct and disappeared in the cauda epididymidis, however, an intense reaction persisted in the lumen. In the distal area of the cauda epididymidis, clear cells were reactive. In the electron microscope, immunogold labeling of reactive principal cells of the middle and distal areas of the initial segment, intermediate zone, and caput epididymidis was detected over cisternae of endoplasmic reticulum, stacks of Golgi saccules, and spherical electron lucent (200-400 nm in diameter) vesicles. The latter were present on the trans face of the Golgi stack, in the vicinity of th Golgi apparatus, and close to the apical cell surface; they are considered as secretory vesicles involved in the secretion of immobilin. In the distal area of the cauda epididymidis, epithelial clear cells showed an intense immunogold labeling over their endocytic apparatus. Immunogold labeling in the lumen of the epididymis was found over a fine flocculent material dispersed between the sperm. This material was especially abundant in the cauda epididymidis and did not appear to be bound to the surface of the sperm. The present results suggest that principal cells of the epididymis are involved in the secretion of immobilin, but that a differential secretory pattern exists between epididymal segments with maximal secretory activity occurring in the intermediate zone and proximal caput epididymidis, while no secretion takes place in the cauda epididymidis. Excess immobilin appears to be endocytosed for degradation by clear cells of the cauda epididymidis.
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PMID:Epithelial cells of the epididymis show regional variations with respect to the secretion of endocytosis of immobilin as revealed by light and electron microscope immunocytochemistry. 154

Rat epididymal glycoprotein DE (37 kDa) associates with the sperm surface during maturation and is localized over the dorsal region of the acrosome. In the present study we examine, by indirect immunofluorescence, the localization of DE after in vitro and in vivo capacitation. While 49% of sperm capacitated in vitro for 5 hr still presented fluorescence over the dorsal region, 51% showed labeling distributed over a domain that corresponds to the equatorial segment of the sperm head. This change in the localization of fluorescence was not associated with sperm deterioration or death and increased gradually as a function of capacitation time, reaching the maximum at 5 hr. The presence of labeling over the equatorial segment results from protein migration and cannot be induced by permeabilization, proteinase, or high ionic strength treatments. The omission of Ca2+ from the standard capacitation medium inhibited the relocalization of DE, and incubation with Ca2+ ionophore A23187 for induction of the acrosome reaction (AR) significantly raised the percentage of cells with DE localized over the equatorial region. Finally, while free and cumulus-associated spermatozoa recovered from the oviducts of in vivo inseminated females presented 15% and 21% of cells with redistribution respectively, all perivitelline (acrosome reacted) spermatozoa showed DE over the equatorial segment. These results indicate that epididymal protein DE migrates to the equatorial segment under in vitro and in vivo capacitating conditions and suggest a possible association between the redistribution of DE and the occurrence of the AR.
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PMID:Redistribution of a rat sperm epididymal glycoprotein after in vitro and in vivo capacitation. 156 25

We report the use of a sensitive and specific enyzme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) to study the expression of protein D, a major androgen-regulated sperm-binding glycoprotein at the protein and mRNA level in different anatomical regions of the rat epididymis. The concentration of protein D in the caput, corpus and cauda region of the epididymis was 10.2 +/- 0.67, 7.3 +/- 0.61 and 22.8 +/- 1.34 ng/micrograms total protein, respectively. The total RNA extracted from the caput, corpus and cauda regions of the rat epididymis was amplified by PCR with oligonucleotide primers specific for the 5' and 3' portion of protein D cDNA. Compared to the caput and cauda region, a significant reduction (greater than 82 +/- 3%) in the expression of protein D mRNA levels was observed for corpus epididymal RNA. This data demonstrates regional differences in the concentration of protein D and suggests that protein D expression may be regulated at the level of mRNA within the corpus epididymidis.
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PMID:Protein D is differentially expressed and regulated in the rat epididymis. 156 91

Tpx-1 is a testis-specific gene that maps on mouse Chromosome (Chr) 17. The deduced TPX-1 protein shows 55% amino acid sequence similarity to acidic epididymal glycoprotein (AEG), assumed to be involved in sperm maturation. In the present study, we determined the genomic structure of the mouse Tpx-1 gene and the cellular localization of its transcripts. The gene was found to contain ten exons, with an unusually large intron (approximately 17.0 kilobase pairs) between exons 8 and 9. In situ hybridization of testicular sections showed that Tpx-1 is transcribed abundantly by haploid male germ cells. A computer search of protein databases revealed that deduced TPX-1/AEG proteins have significant sequence similarity (approximately 30%) to two non-mammalian proteins: "pathogenesis-related" proteins 1 of tobaccos, and venom sac proteins of white-face hornets, known as Dol m V. Amino acid residues encoded by exon 10 of the Tpx-1 gene and most of those encoded by exon 9 were absent in the non-mammalian proteins. This result suggests that the ancestor of Tpx-1 acquired exons 9 and 10 after its divergence from the ancestors of the plant and insect proteins.
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PMID:The mouse male germ cell-specific gene Tpx-1: molecular structure, mode of expression in spermatogenesis, and sequence similarity to two non-mammalian genes. 163 86

To investigate surface glycoprotein changes during post-testicular maturation, plasma membranes were isolated from proximal caput, distal caput, and cauda epididymal rat spermatozoa. Membrane glycoproteins were identified on Western blots of SDS-PAGE fractionated samples using biotinylated lectins and Vecta-stain reagents; these were compared to glycoproteins present in cauda epididymal luminal fluid. Lens culinaris agglutinin, Pisum sativum agglutinin, peanut agglutinin, wheat germ agglutinin, Ricinus communis agglutinin, Ulaex europaeus agglutinin, and Dolichol biflorus agglutinin each bound a specific subset of the polypeptides present. Several types of glycoprotein changes were noted including their appearance, loss, alteration of staining intensity, and alteration of electrophoretic mobility. Some maturation-dependent sperm surface glycoproteins co-migrated with glycoproteins present in epididymal fluid. This approach of direct analysis of the glycoproteins in purified plasma membranes identifies a broader spectrum of maturation-related surface changes occurring within the epididymis than are noted with surface labeling procedures.
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PMID:Glycoprotein changes in the rat sperm plasma membrane during maturation in the epididymis. 171 14

Albumin reduces capillary permeability and acts as a carrier for various small molecules. Recently, we identified a 60-kDa sialoglycoprotein (gp60) on the surface of cultured rat microvascular endothelial cells (MEC) that binds albumin and antiglycophorin serum (alpha-gp). We verified that alpha-gp recognizes the albumin-binding gp60 by affinity, purifying proteins from MEC extracts using immobilized albumin. gp60 was immunoblotted with alpha-gp only when the MEC extract was reacted with albumin and not in controls. We immunoprecipitated gp60 from biosynthetically radiolabeled MEC lysates and from extracts containing endothelial surface proteins of isolated rat hearts that were radioiodinated in situ. gp60 was immunoblotted selectively in rat tissue microvascular beds lined with continuous endothelium (heart, lung, diaphragm, fat, skeletal muscle, mesentery, and duodenal muscularis but not cortical brain) and not those exclusively lined with fenestrated or sinusoidal endothelium (adrenal, pancreas, liver, and small intestinal mucosa). MEC isolated from rat heart, lung, and epididymal fat pad expressed gp60 and bound albumin, whereas various nonendothelial cells and brain-derived MEC did not. gp60 is an albumin-binding glycoprotein expressed specifically on the surface of continuous endothelium that binds albumin apparently not only to initiate its transcytosis via plasmalemmal vesicles but also to increase capillary permselectivity.
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PMID:gp60 is an albumin-binding glycoprotein expressed by continuous endothelium involved in albumin transcytosis. 173 16

The cell surface glycoproteins of goat epididymal maturing spermatozoa have been investigated using lectins as surface probes that interact with specific sugars with high affinity. Concanavalin A (ConA) and wheat-germ agglutinin (WGA) showed high affinity for mature cauda epididymal sperm agglutination, whereas RCA2, kidney beans lectin and peanut agglutinin caused much lower or little agglutination of the cells. The mature sperm exhibited markedly higher efficacy than the immature caput epididymal sperm for binding both ConA and WGA, as evidenced by sperm agglutination and the binding of the fluorescence isothiocyanate (FITC)-labelled lectins. FITC-ConA binds uniformly to the entire mature sperm surface whereas FITC-WGA binds to the acrosomal cap region of the head. The FITC-RCA2 mainly labelled the posterior head of mature cauda sperm. However, no WGA-specific glycoprotein receptors could be detected in sperm plasma membrane (PM) by WGA-Sepharose affinity chromatography. The data implied that the epididymal sperm maturation is associated with a marked increase in the ConA/WGA receptors and that WGA receptors may be glycolipids rather than glycoproteins. Analysis of the ConA receptors of cauda sperm PM identified by ConA-Sepharose affinity chromatography and subsequent resolution in SDS-PAGE demonstrated the presence of five glycopolypeptides of different concentrations (98, 96, 43, 27 and 17 kDa) of goat sperm membrane. The immunoblot of these ConA-specific glycopeptides with anti-sperm membrane antiserum showed that 98- and 96-kDa receptors are immunoresponsive.
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PMID:Goat sperm membrane: lectin-binding sites of sperm surface and lectin affinity chromatography of the mature sperm membrane antigens. 175 26

Mammalian sperm acquire functional maturity as they move from the caput to the cauda epididymidis. Changes occur in the protein/glycoprotein composition of the sperm plasma membrane during this time, and may be essential to the maturation process. The production of monoclonal antibody (Mab) probes to the maturation-specific molecules has been difficult since new proteins comprise a minor portion of total membrane proteins. This report describes a protocol for enhancing the production of Mabs to maturation specific molecules. By injecting neonatal mice with caput epididymal sperm plasma membranes, in combination with chemical immunosuppression at adulthood, the mice were made tolerant to the antigens expressed on the caput sperm membranes. Subsequent immunization with cauda epididymal sperm plasma membranes allowed the production of Mabs to the maturation-specific moieties without the necessity for extensive antigen purification procedures. The majority of the resulting Mabs recognize cauda, not caput, epididymal sperm plasma membranes as determined by enzyme-linked immunosorbent assay (ELISA), immunocytochemistry on unfixed cells, and Western blot analyses, even though the protein profile from caput epididymal sperm plasma membranes is very similar to that from cauda membranes. The five Mabs described also recognize cauda fluid antigens, suggesting that the maturational changes on the sperm plasma membranes arise from interactions with the epididymal fluid. Use of the tolerization/immunosuppression protocol has provided Mab tools to assist in the study of sperm maturation during epididymal transit.
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PMID:Use of neonatal tolerization and chemical immunosuppression for the production of monoclonal antibodies to maturation-specific sperm surface molecules. 176 66

The epididymal tubule is a dynamic structure, in which spermatozoa undergo distinct physiological and morphological changes. The epithelial cells lining the ductuli vary dramatically in their histochemical and cytological properties according to the region of the tubule in which they are located. Additionally, regional variation is observed regarding the biosynthetic, secretory, and absorptive properties of the epithelial cells. Using in situ histochemical analysis, we document here the region-specific expression of a variety of genes that are transcriptionally active in the adult rat epididymis. Radiolabeled antisense riboprobes were used to localize, within the efferent duct/caput epididymis, transcripts encoding protein B/C, protein D/E (acidic epididymal glycoprotein), sulphated glycoprotein 1, sulphated glycoprotein 2, cellular retinol-binding protein, and the neuroendocrine peptide precursor proenkephalin. Each species of mRNA exhibits a unique pattern of hybridization, revealing that gene transcription within the efferent duct/caput epididymis is also highly region specific. This observation may partially elucidate the molecular basis underlying the phenomenon of regional alterations in the composition of protein factors within the tubule lumen.
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PMID:In situ histochemical analysis of region-specific gene expression in the adult rat epididymis. 178 83

Clusterin (sulfated glycoprotein-2) is a heterodimeric glycoprotein synthesized and secreted by rat Sertoli cells. An antigenically similar form is synthesized and secreted by the epididymis. The goal of this study was to define the epididymal regions in which clusterin is present and the regions in which clusterin is secreted and interacts with developing spermatozoa. Seminiferous tubule (STF), caput, corpus, and cauda fluids were collected by micropuncture and/or microperfusion and two-dimensional Western blot analysis was performed with a polyclonal antibody directed against Sertoli cell clusterin. Clusterin was found in both STF and epididymal fluid. STF contained predominantly the clusterin heavy chain (45 kd); however, a 70 Kd heterodimer was present under nonreducing conditions. Two subunits of clusterin with lower molecular weights (41 kd, heavy chain; 32 kd, light chain) and higher isoelectric points were present in the luminal fluid of all epididymal regions. The intraluminal levels of the heavy and light chains decreased from caput to cauda. Analysis by two-dimensional gel electrophoresis of proteins secreted directly into the epididymal luminal fluid revealed that clusterin was secreted by caput epithelium and not by the corpus and cauda epithelium. Western blots of membrane extracts from testicular, caput, and cauda spermatozoa revealed that testicular clusterin was associated with testicular sperm and epididymal clusterin with predominantly caput sperm. Our findings suggest that clusterin is secreted into the caput epididymal lumen, where it binds to sperm and then dissociates from sperm to be endocytosed by cells of the distal epididymal epithelium.
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PMID:In vivo secretion and association of clusterin (SGP-2) in luminal fluid with spermatozoa in the rat testis and epididymis. 178 89


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