title: Palmitoylation of STREX domain confers cerebroside sensitivity to the BKCa channel.
abstract: Our previous study reported that cerebrosides from traditional Chinese medicine Baifuzi directly interact with the STREX domain of BKCa channels, which in turn results in the therapeutic effect of Baifuzi on ischemic stroke. However, it is not known how cerebrosides in the plasma membrane could interact with the STREX domain that is in the cytoplasmic side. Using patch-clamp technique, effects of different cerebrosides on the BKCa channel were studied by measuring single channel currents in CHO cells expressing wild type or mutated BKCa channels. Palmitoylation of the STREX domain was removed either by site-directed mutagenesis or pharmacological inhibition. Removal of palmitoylation sites at C646 and C647 by mutating the residues to Ala abolished the ability of cerebrosides to activate the BKCa channel. In contrast, the mutation neither changed the single channel conductance nor voltage sensitivity of the channel. Both palmitoylation inhibitors tunicamycin and palmitic acid analog 2-bromopalmitate attenuated the activation of the BKCa channel by cerebrosides. Furthermore, confocal images on STREX-EGFP fragments demonstrated that STREX fragments no longer associated with the plasma membrane when the palmitoylation was removed or blocked. These findings suggest that palmitoylation of the STREX domain is necessary for cerebrosides to activate the BKCa channel and provide insight into the mechanism of how Baifuzi could exert therapeutic effect on ischemic stroke.
authors.affiliation: Department of Basic Medical Sciences, Medical College of Xiamen University, Xiang'an Nan Lu, Xiamen 361102, China.
authors.forename: Yujiao
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Basic Medical Sciences, Medical College of Xiamen University, Xiang'an Nan Lu, Xiamen 361102, China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Basic Medical Sciences, Medical College of Xiamen University, Xiang'an Nan Lu, Xiamen 361102, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zou
authors.affiliation: Department of Basic Medical Sciences, Medical College of Xiamen University, Xiang'an Nan Lu, Xiamen 361102, China.
authors.forename: Mingyan
authors.initials: M
authors.lastname: Wang
authors.affiliation: College of Pharmaceutical Sciences, Zhejiang University, 866 Yuhangtang Rd, Hangzhou 310058, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Qi
authors.affiliation: Department of Basic Medical Sciences, Medical College of Xiamen University, Xiang'an Nan Lu, Xiamen 361102, China. Electronic address: qizhi@xmu.edu.cn.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Qi
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016466:CHO Cells; D002462:Cell Membrane / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002554:Cerebrosides / Q000737:chemistry / Q000494:pharmacology*; D002645:Chickens; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects*; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054878:Lipoylation / Q000187:drug effects / Q000502:physiology*; D008516:Medicine, Chinese Traditional / Q000379:methods; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D018408:Patch-Clamp Techniques; D017434:Protein Structure, Tertiary; D020521:Stroke / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism
chemical_list: D030161:Avian Proteins; D002554:Cerebrosides; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits
keywords: BK(Ca) channel; Cerebroside; Ischemic stroke; Palmitoylation; STREX domain