The calcium-binding EF-hand in polycystin-L is not a domain for channel activation and ensuing inactivation

被引:38
作者
Li, Q [1 ]
Liu, Y [1 ]
Zhao, W [1 ]
Chen, XZ [1 ]
机构
[1] Univ Alberta, Dept Physiol, Edmonton, AB T6G 2H7, Canada
基金
加拿大健康研究院;
关键词
autosomal dominant polycystic kidney disease; splice variant; cation channel; calcium; electrophysiology; Xenopus oocyte;
D O I
10.1016/S0014-5793(02)02513-9
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Polycystin-L (PCL) shares high homology with polycystin-2, the product of polycystic kidney disease gene-2. It was previously shown that the PCL forms a non-selective cation channel activated by calcium influx. However, it remains unclear whether calcium activates/inactivates PCL by binding to the EF-hand motif located on the cytoplasmic carboxyl-terminus. Here we obtained two PCL splice variants from liver (PCL-LV, lacking the EF-hand) and testis (PCL-TS, lacking 45 amino acids on the carboxyl tail) using PCR-based approaches. When expressed in Xenopus oocytes and studied using electrophysiology both splice variants exhibited basal cation channel activity and calcium-induced channel activation. While PCL-TS displayed similar activation to PCL, PCL-LV exhibited a threefold increased activation. All five PCL C-terminal artificial truncation mutants also exhibited basal and calcium-activated channel activities, in particular the mutant T622X lacking the EF-hand was associated with increased activation. Our data demonstrate that the EF-hand and other parts of the carboxyl tail of PCL are not determinants of channel activation/inactivation although the EF-hand seems to be involved in the modulation of these processes. (C) 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.
引用
收藏
页码:270 / 278
页数:9
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