Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 25-kDa epididymal secretory protein (MEP 9), isolated from mouse epididymal fluid, has recently been characterized in our laboratory [Rankin et al., Biol Reprod 1992; 46:747-766]. The polyclonal antibody raised against this protein was found to recognize a 25-kDa component in epididymal fluid and testicular extract. The 25-kDa testicular antigen (MTP) was purified by means of ammonium sulfate precipitation, gel filtration, and anion-exchange chromatography; MTP was found to be similar to MEP 9 in several properties including molecular mass (25 kDa), isoelectric point (pI 6.0), and immunoreactivity when the proteins were resolved in the presence of SDS (one-dimensional and two-dimensional PAGE). However, when the proteins were resolved under non-denaturing conditions, MTP showed strong immunoreactivity while MEP 9 did not. This observation suggests that although the 25-kDa antigens from the epididymal fluid and testicular extract are quite similar, they may have different immunological conformations. When analyzed for amino acid composition and partial amino acid sequence, the testicular antigen showed substantial homology (> 80%) with a phosphatidylethanolamine-binding protein characterized from bovine brain. MTP also showed phosphatidylethanolamine-binding activity (Kd = 1.95 x 10(-5) M, Bmax = 1.86 nmol/micrograms MTP), suggesting that the mouse 25-kDa protein is a member of the phospholipid-binding protein family and may have a role in lipid metabolism during sperm maturation.
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PMID:Isolation and characterization of a 25-kilodalton protein from mouse testis: sequence homology with a phospholipid-binding protein. 147 9

We have recently observed that a polyclonal antibody raised against a mouse epididymal luminal fluid protein (MEP 9) recognizes a 25-kDa antigen in mouse testis and epididymis [Rankin et al., Biol Reprod 1992; 46:747-766]. This antigen was localized by light and electron microscopic immunohistochemistry. The immunoreactivity in the testis was found in the residual cytoplasm of the elongated spermatids, in the residual bodies, and in the cytoplasmic droplets of spermatozoa. In the epididymis, the epithelial principal cells were stained from the distal caput to the distal cauda. Immunogold labeling in the principal cells showed diffuse distribution without preferential accumulation in either the endocytic or the secretory apparatus of the cells. In the epididymal lumen, the immunoreactivity was restricted to the sperm cytoplasmic droplets. No membrane-specific labeling was observed in luminal spermatozoa, cytoplasmic droplets, or isolated sperm plasma membranes. Three weeks after hemicastration or severance of the efferent ducts, a normal distribution of the immunoreactive sites was found in the epididymis. Immunoreactivity, was also detected in the epididymal epithelium of immature mice as well as in that of XXSxr male mice having no spermatozoa in the epididymis. These results suggest that the immunoreactivity seen in the principal cells originates from synthesis rather than endocytosis of the testicular protein from disrupted cytoplasmic droplets. Furthermore, these results suggest that the 25-kDa protein is synthesized independently by both testis and epididymis.
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PMID:Immunolocalization of a 25-kilodalton protein in mouse testis and epididymis. 147 10

Three murine epididymal secretory proteins have been characterized by their site of synthesis, sperm association, and tissue localization by use of polyclonal antisera and immunochemistry. Mouse epididymal protein 7 (MEP 7) was localized initially within the supranuclear regions of some principal epithelial cells in the proximal corpus while other cells remained unstained. In the mid-proximal corpus, all principal cells and stereocilia were stained, and luminal staining increased from corpus to cauda. Some clear cells in the distal corpus and cauda also showed immunoperoxidase staining. Sequential extraction of caudal spermatozoa indicated that MEP 7 was predominantly loosely associated with spermatozoa and that only a small amount of MEP 7 required detergent to extract it from spermatozoa. Examination of other rodent caudal fluids revealed a related protein in rat caudal fluid of 32 kDa, and amino acid sequence analysis of MEP 7 showed a 68% sequence similarity with rat proteins AEG and D/E. MEP 9 immunolocalized within the cytoplasm of all principal cells of the distal caput. In a transition zone between the distal caput and the corpus, some principal cells were stained while others were not. Distal to the corpus, the principal cell staining gradually decreased. In the distal caput and proximal corpus, large heavily stained droplets associated with spermatozoa were seen in the lumen. The staining intensity of these droplets also decreased from corpus to cauda. The clear cells of the distal corpus and cauda did not stain with the antibody to MEP 9. Sequential extraction of caudal spermatozoa showed that some MEP 9 was extractable under low-salt conditions, whereas extraction with 0.1% Triton X-100 was required to remove all MEP 9, indicating it was firmly associated with spermatozoa. The antibody to MEP 9 cross-reacted with a 25-kDa protein present in rat caudal fluid. MEP 10 was localized within the cytoplasm of the principal cells, the stereocilia, and the lumen of the epididymis at the junction of the distal caput and corpus. In the distal corpus, a large number of clear cells were stained, but very few of these cells stained in the cauda. MEP 10 dissociated completely from caudal spermatozoa under low-salt conditions, indicating that it was not firmly bound to spermatozoa. The antiserum to MEP 10 cross-reacted with proteins present in rat and guinea pig caudal fluid. The related rat protein migrated at approximately 20 kDa. Amino acid sequence analysis of MEP 10 revealed an 86% sequence similarity with rat proteins B and C.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Isolation, immunolocalization, and sperm-association of three proteins of 18, 25, and 29 kilodaltons secreted by the mouse epididymis. 159 32

In previous studies we reported the synthesis, secretion, and immunolocalization at the light microscopic level of two mouse epididymal proteins, MEP 7 and MEP 10 [Rankin et al. (1992b), Biol. Reprod., 46:747-766]. MEP 7 is the mouse homologue of the rat metalloproteins, AEG/D and E, and MEP 10 is the mouse homologue of the rat retinoic acid binding proteins, B and C. We now describe the immunolocalization of MEP 7 and MEP 10 in the mouse epididymis at the electron microscopic level. MEP 7 was localized in the Golgi apparatus, in small electron-lucent secretory vesicles, and on microvilli of the principal cells from the distal caput epididymidis to the cauda. The luminal contents were also immunoreactive in these regions of the epididymis. Although some gold particles were associated with the sperm surface, there was no selective concentration of these particles. In addition, MEP 7 was localized in large (600 nm) supranuclear endocytic vesicles and in infranuclear lysosomes. MEP 10 immunoreactivity was also seen on the microvilli of the principal cells of the distal caput and corpus and the luminal contents from the distal caput to the cauda epididymidis. There was no association of gold particles with the sperm surface. In contrast to MEP 7, there was no detectable MEP 10 immunoreactivity on the organelles of the principal cells involved in protein secretion or endocytosis. Clear cells also demonstrated immunoreactivity to MEP 7 and MEP 10. However, the intensity of immunolabeling, and the number of clear cells labeled, was greater with MEP 10 than MEP 7. In the case of MEP 7, the gold particles were located on the large supranuclear endocytic vesicles and on some infranuclear lysosomes, from the proximal corpus to the middle cauda, while in the case of MEP 10, gold particles were predominantly present in infranuclear lysosomes from the distal caput to the middle cauda. These results suggest that the principal cells are involved in both the secretion and endocytosis of MEP 7. The MEP 10 and MEP 7 proteins present in the lumen of the mouse epididymis are endocytosed from the lumen and degraded in the clear cells. However, the process of endocytosis by the clear cells of these two proteins appears to be different.
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PMID:Electron microscopic immunolocalization of the 18 and 29 kilodalton secretory proteins in the mouse epididymis: evidence for differential uptake by clear cells. 771 18

A complementary DNA encoding the mouse epididymal secretory protein MEP 10 (mouse epididymal protein 10) was cloned and is now renamed murine epididymal retinoic acid binding protein (mE-RABP). The analysis of the predicted primary amino acid sequence showed that mE-RABP has a 75% identity with rat ESP I (epididymal secretory protein I), another epididymal retinoic acid-binding protein. The homology strongly suggests that mE-RABP is the mouse orthologue of rat ESP I. A computer analysis of the predicted three-dimensional structure confirmed that mE-RABP can accommodate retinoic acid as ligand. In the rat, ESP I messenger RNA (mRNA) is expressed in the efferent ducts and in the entire caput epididymidis. However, in the mouse, the expression of a 950-bp mE-RABP mRNA was detected only in principal cells of the mid/distal caput epididymidis, suggesting that the regulation of region-specific expression is different in rat and mouse. Northern blot analyses showed that mE-RABP gene expression is no longer detected 10 days after castration but progressively rebounds between days 15 and 60. However, mE-RABP protein could not be detected by Western blot 30 days after castration. Androgen replacement, begun 5 days after castration and continued for 4 days restored significant expression of mE-RABP mRNA. Efferent duct ligation for 10 days did not affect gene expression. Taken together, these results indicate that mE-RABP mRNA expression is regulated by androgens but not by testicular factors. The overall similarity in the primary amino acid sequence of mE-RABP with ESP I and other members of the lipocalin superfamily suggests that they are evolutionarily related.
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PMID:Molecular cloning and hormonal regulation of a murine epididymal retinoic acid-binding protein messenger ribonucleic acid. 960 8