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The calcium‐binding EF‐hand in polycystin‐L is not a domain for channel activation and ensuing inactivation
Author(s) -
Li Qiang,
Liu Yan,
Zhao Wei,
Chen Xing-Zhen
Publication year - 2002
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(02)02513-9
Subject(s) - xenopus , chemistry , r type calcium channel , mutant , microbiology and biotechnology , calcium , ef hand , biophysics , n type calcium channel , voltage dependent calcium channel , calcium channel , calcium binding protein , biochemistry , t type calcium channel , biology , gene , organic chemistry
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 three‐fold 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.