Role of the C-Terminus of the High-Conductance Calcium-Activated Potassium Channel in Channel Structure and Function
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- 作者：William A. Schmalhofer ; Manuel Sanchez ; Ge Dai ; Ashvin Dewan ; Lorena Secades ; Markus Hanner ; Hans-Guenther Knaus ; Owen B. McManus ; Martin Kohler ; Gregory J. Kaczorowski ; and Maria L. Garcia
- 刊名：Biochemistry
- 出版年：2005
- 出版时间：August 2, 2005
- 年：2005
- 卷：44
- 期：30
- 页码：10135 - 10144
- 全文大小：301K
- 年卷期：v.44,no.30(August 2, 2005)
- ISSN：1520-4995
文摘
The role of ion channels in cell physiology is regulated by processes occurring after proteinbiosynthesis, which are critical for both channel function and targeting of channels to appropriate cellcompartments. Here we apply biochemical and electrophysiological methods to investigate the role of thehigh-conductance, calcium-activated potassium (Maxi-K) channel C-terminal domain in channel tetramerization, association with the 
1 subunit, trafficking of the channel complex to the cell surface, and channelfunction. No evidence for channel tetramerization, cell surface expression, or function was observed withMaxi-K1-323, a construct truncated three residues after the S6 transmembrane domain. However, Maxi-K1-343 and Maxi-K1-441 are able to form tetramers and to associate with the 1 subunit. Maxi-K1-343-1and Maxi-K1-441-1 complexes are efficiently targeted to the cell surface and cannot be pharmacologicallydistinguished from full-length channels in binding experiments but do not form functional channels. Maxi-K1-651 forms tetramers and associates with 1; however, the complex is not present at the cell surface,but is retained intracellularly. Maxi-K1-651 surface expression and channel function can be fully rescuedafter coexpression with its C-terminal complement, Maxi-K652-1113. However coexpression of Maxi-K1-343and Maxi-K1-441 with their respective C-terminal complements did not rescue channel function. Together,these data demonstrate that the domain(s) in the Maxi-K channel necessary for formation of tetramers,coassembly with the 1 subunit, and cell surface expression resides within the S0-S6 linker domain ofthe protein, and that structural constraints within the gating ring in the C-terminal region can regulatetrafficking and function of constructs truncated in this region.
1 subunit, trafficking of the channel complex to the cell surface, and channelfunction. No evidence for channel tetramerization, cell surface expression, or function was observed withMaxi-K1-323, a construct truncated three residues after the S6 transmembrane domain. However, Maxi-K1-343 and Maxi-K1-441 are able to form tetramers and to associate with the 1 subunit. Maxi-K1-343-1and Maxi-K1-441-1 complexes are efficiently targeted to the cell surface and cannot be pharmacologicallydistinguished from full-length channels in binding experiments but do not form functional channels. Maxi-K1-651 forms tetramers and associates with 1; however, the complex is not present at the cell surface,but is retained intracellularly. Maxi-K1-651 surface expression and channel function can be fully rescuedafter coexpression with its C-terminal complement, Maxi-K652-1113. However coexpression of Maxi-K1-343and Maxi-K1-441 with their respective C-terminal complements did not rescue channel function. Together,these data demonstrate that the domain(s) in the Maxi-K channel necessary for formation of tetramers,coassembly with the 1 subunit, and cell surface expression resides within the S0-S6 linker domain ofthe protein, and that structural constraints within the gating ring in the C-terminal region can regulatetrafficking and function of constructs truncated in this region.© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |