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A single amino acid mutation attenuates rundown of voltage‐gated calcium channels
Author(s) -
Zhen Xiao-Guang,
Xie Cheng,
Yamada Yoichi,
Zhang Yun,
Doyle Christina,
Yang Jian
Publication year - 2006
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/j.febslet.2006.09.027
Subject(s) - voltage dependent calcium channel , patch clamp , biophysics , chemistry , ion channel , mutation , amino acid , calcium channel , calcium , biochemistry , biology , receptor , organic chemistry , gene
The activity of voltage‐gated calcium channels (VGCCs) decreases with time in whole‐cell and inside‐out patch‐clamp recordings. In this study we found that substituting a single amino acid (I1520) at the intracellular end of IIIS6 in the α 1 subunit of P/Q‐type Ca 2+ channels with histidine or aspartate greatly attenuated channel rundown in inside‐out patch‐clamp recordings. The homologous mutations also slowed rundown of N‐ and L‐type Ca 2+ channels, albeit to a lesser degree. In P/Q‐type channels, the attenuation of rundown is accompanied by an increased apparent affinity for phosphatidylinositol‐4,5‐bisphosphate, which has been shown to be critical for maintaining Ca 2+ channel activity [L. Wu, C.S. Bauer, X.‐G. Zhen, C. Xie, J. Yang, Dual regulation of voltage‐gated calcium channels by PtdIns(4,5)P2. Nature 419 (2002) 947–952]. Furthermore, the histidine mutation significantly stabilized the open state, making the channels easier to open, slower to close, harder to inactivate and faster to recover from inactivation. Our finding that mutation of a single amino acid can greatly attenuate rundown provides an easy and efficient way to slow the rundown of VGCCs, facilitating functional studies that require direct access to the cytoplasmic side of the channel.