An investigation of the occurrence and properties of the mitochondrial intermediate-conductance Ca²⁺-activated K⁺ channel mtK_Ca3.1

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• 作者：Nicola Sassi ; Umberto De Marchi ; Bernard Fioretti ; Lucia Biasutto ; Erich Gulbins ; Fabio Franciolini ; Ildikò ; Szabò ; Mario Zoratti
• 关键词：Inner mitochondrial membrane ; IK(Ca) ; HeLa cells ; Patch-cl Calcium ; TRAM-34
• 刊名：Biochimica et Biophysica Acta (BBA)/Bioenergetics
• 出版年：2010
• 出版时间：June-July 2010
• 年：2010
• 卷：1797
• 期：6-7
• 页码：1260-1267
• 全文大小：821 K

文摘

The mitochondrial intermediate-conductance Ca²⁺-activated K⁺ channel mtK_Ca3.1 has recently been discovered in the HCT116 colon tumor-derived cell line, which expresses relatively high levels of this protein also in the plasma membrane. Electrophysiological recordings revealed that the channel can exhibit different conductance states and kinetic modes, which we tentatively ascribe to post-translational modifications. To verify whether the localization of this channel in mitochondria might be a peculiarity of these cells or a more widespread feature we have checked for the presence of mtK_Ca3.1 in a few other cell lines using biochemical and electrophysiological approaches. It turned out to be present at least in some of the cells investigated. Functional assays explored the possibility that mtK_Ca3.1 might be involved in cell proliferation or play a role similar to that of the Shaker-type K_V1.3 channel in lymphocytes, which interacts with outer mitochondrial membrane-inserted Bax thereby promoting apoptosis (Szabò, I. et al., Proc. Natl. Acad Sci. USA 105 (2008) 14861–14866). A specific K_Ca3.1 inhibitor however did not have any detectable effect on cell proliferation or death.