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)

Acidic epididymal fluid mainly accounts for sperm quiescence during storage in the epididymis. Carbonic anhydrase (CA) is an enzyme involved in proton and bicarbonate secretion in various epithelia. Therefore, we elucidated the distribution of the cytoplasmic (CA II) and membrane-associated (CA IV) isoenzymes in rat epididymis using polyclonal rabbit antisera to these isoenzymes in conjunction with immunohistochemical and immunoblotting techniques. CA IV was localized in the apical plasma membrane of principal epithelial cells in the distal caput, corpus, and proximal cauda epididymides, the staining intensity being most intense in the corpus segment. The epithelium of the ductus deferens, seminal vesicle, and ventral prostate was devoid of staining. CA II was present in the narrow cells of the initial segment and in the epithelial cells of the distal caput, corpus, and proximal cauda epididymides. Immunoblotting of different epididymal segments for CA IV and II revealed with anti-CA IV serum a distinct 39-kDa polypeptide band in the corpus segment and with anti-CA II serum a 29-kDa polypeptide band in all segments, with the band most intense, however, in the corpus segment. Our results imply that in rat epididymis both bicarbonate reabsorption and proton secretion are involved in epididymal fluid acidification. By analogy with the kidney proximal tubule, we suggest that CA IV is involved in bicarbonate reabsorption mainly occurring in the corpus epididymidis. The presence of CA II in epididymal epithelial cells is probably involved in the supply of protons for secretion mediated by various ion transport mediators.
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PMID:Expression of carbonic anhydrase isoenzymes IV and II in rat epididymal duct. 763 42

Carbonic anhydrase (CA) is implicated in the acidification of epididymal fluid and thereby in the regulation of sperm maturation and motility. Among the CA isoenzymes, CA IV and II have been shown to be present in the rat epididymal duct epithelium. In the present study, we examined the expression and androgen regulation of CA IV and II mRNAs along the epididymal duct. Northern blot analysis revealed the presence of CA II mRNA in all regions of the epididymis with the strongest signal in the corpus region, while CA IV mRNA was expressed predominantly in the corpus epididymidis. Three days after bilateral castration, CA IV and II mRNAs were decreased by 80-90% in the corpus epididymidis. Testosterone (T) replacement maintained the expression of CA mRNAs at 50-60% of the control levels, indicating that circulating androgens alone are not sufficient to recover the CA expression in the corpus region. However, unilateral castration did not affect the mRNA levels of CA IV and II, suggesting that factors in testicular fluid do not play a major role in the regulation of CA expression in the corpus epididymidis. Immunoblot analysis showed that CA IV protein levels decreased 3 days after castration, while T administration maintained the protein expression virtually at the precastration levels. These data demonstrate that mRNAs for CA IV and II are predominantly expressed in the corpus region of the rat epididymis and can be regulated by androgens in that region. The present data suggest that the regulation of CA expression in the corpus epididymidis by androgens contributes to the known androgen effects on epididymal acidification.
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PMID:Regional expression and androgen regulation of carbonic anhydrase IV and II in the adult rat epididymis. 1056 98