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)

The nucleoside transport systems in cultured epididymal epithelium were characterized and found to be similar between the proximal (caput and corpus) and distal (cauda) regions of the epididymis. Functional studies revealed that 70% of the total nucleoside uptake was Na(+) dependent, while 30% was Na(+) independent. The Na(+)-independent nucleoside transport was mediated by both the equilibrative nitrobenzylthioinosine (NBMPR)-sensitive system (40%) and the NBMPR-insensitive system (60%), which was supported by a biphasic dose response to NBMPR inhibition. The Na(+)-dependent [(3)H]uridine uptake was selectively inhibited 80% by purine nucleosides, indicating that the purine nucleoside-selective N1 system is predominant. Since Na(+)-dependent [(3)H]guanosine uptake was inhibited by thymidine by 20% and Na(+)-dependent [(3)H]thymidine uptake was broadly inhibited by purine and pyrimidine nucleosides, this suggested the presence of the broadly selective N3 system accounting for 20% of Na(+)-dependent nucleoside uptake. Results of RT-PCR confirmed the presence of mRNA for equilibrative nucleoside transporter (ENT) 1, ENT2, and concentrative nucleoside transporter (CNT) 2 and the absence of CNT1. It is suggested that the nucleoside transporters in epididymis may be important for sperm maturation by regulating the extracellular concentration of adenosine in epididymal plasma.
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PMID:Characterization of nucleoside transport systems in cultured rat epididymal epithelium. 1128 19

The epididymis relies on transporters for the secretion of nucleosides and influence the disposition of nucleoside analogs (NSA). Since these compounds can cross the blood-testis barrier (BTB), it is important to understand if the epididymis reabsorbs NSA drugs. The purpose of this study is to determine the localization of nucleoside transporters expressed within rat epididymis to demonstrate the potential of epididymal reabsorption. Using immunohistochemistry, we determined that equilibrative nucleoside transporter 1 (ENT1) is localized to the basolateral membrane of epithelial cells, ENT2 is expressed in the nucleus of the epithelium and CNT2 is expressed by basal cells. The expression pattern for these transporters suggests that nucleosides are able to access the epithelial cells of the epididymal duct via the blood, but not from the lumen. We did not find any evidence for a transepithelial reabsorption pathway indicating the NSA drugs that cross the BTB remain within the epididymis.
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PMID:Localization of nucleoside transporters in rat epididymis. 2832 28