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Molecular characterization of a novel UT-A urea transporter isoform (UT-5) in testis
被引:68
作者:
Fenton, RA
Howorth, A
Cooper, GJ
Meccariello, R
Morris, ID
Smith, CP
机构:
[1] Univ Manchester, Sch Biol Sci, Manchester M13 9PT, Lancs, England
[2] Univ Naples 2, Fac Med & Chirurg, I-1680168 Naples, Italy
来源:
AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY
|
2000年
/
279卷
/
05期
关键词:
urea transporter;
membrane protein;
testes;
mouse;
D O I:
10.1152/ajpcell.2000.279.5.C1425
中图分类号:
Q2 [细胞生物学];
学科分类号:
071009 ;
090102 ;
摘要:
Urea movement across plasma membranes is modulated by specialized transporter proteins that are products of two genes, termed UT-A and UT-B. These proteins play key roles in the urinary concentrating mechanism and fluid homeostasis. We have isolated and characterized a 1.4-kb cDNA from testes encoding a new isoform (UT-A5) belonging to the UT-A transporter family. For comparison, we also isolated a 2.0-kb cDNA from mouse kidney inner medulla encoding the mouse UT-A3 homologue. The UT-A5 cDNA has a putative open reading frame encoding a 323- amino acid protein, making UT-A5 the smallest UT- A family member in terms of molecular size. Its putative topology is of particular interest, because it calls into question earlier models of UT-A transporter structure. Expression of UT-A5 cRNA in Xenopus oocytes mediates phloretin-inhibitable urea uptake and does not translocate water. The distribution of UT-A5 mRNA is restricted to the peritubular myoid cells forming the outermost layer of the seminiferous tubules within the testes and is not detected in kidney. UT-A5 mRNA levels are coordinated with the stage of testes development and increase 15 days postpartum, commensurate with the start of seminiferous tubule fluid movement.
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页码:C1425 / C1431
页数:7
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