title: Direct interaction between BKCa potassium channel and microtubule-associated protein 1A.
abstract: The BKCa channel, a potassium channel that is allosterically activated by voltage and calcium, is expressed in both excitable and non-excitable cells. The channel plays an important role in regulating membrane excitability. The channel activity can be modulated by post-translational modifications such as phosphorylation. Recently, hippocampal BKCa channels were shown to be directly modulated by assembly/disassembly of the submembranous actin cytoskeleton. Here, we report that the BKCa channel physically interacts with the light chain of microtubule associated protein 1A (MAP1A). The light chain was isolated in a yeast two-hybrid screen of a human brain cDNA library. The specificity of the interaction was demonstrated in biochemical experiments utilizing GST fusion protein pulldown assays and reciprocal co-immunoprecipitations from rat brain. Furthermore, utilizing immunofluorescence, the BKCa channel and MAP1A co-localize in the Purkinje cell layer of the cerebellum. These studies identify a novel interaction between the C-terminal tail of the BKCa channel and the light chain of MAP1A, which enables channel association with and modulation by the cytoskeleton.
authors.affiliation: Department of Physiology and Cellular Biophysics, Columbia University College of Physicians and Surgeons, New York, NY, USA.
authors.forename: Soo Mi
authors.initials: SM
authors.lastname: Park
authors.forename: Guoxia
authors.initials: G
authors.lastname: Liu
authors.forename: Anup
authors.initials: A
authors.lastname: Kubal
authors.forename: Matthew
authors.initials: M
authors.lastname: Fury
authors.forename: Luxiang
authors.initials: L
authors.lastname: Cao
authors.forename: Steven O
authors.initials: SO
authors.lastname: Marx
mesh_terms: D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002531:Cerebellum / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D015723:Gene Library; D005982:Glutathione Transferase / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism; D007150:Immunohistochemistry; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D015221:Potassium Channels / Q000737:chemistry* / Q000378:metabolism*; D011233:Precipitin Tests; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D000199:Actins; D018076:DNA, Complementary; C494842:Kcnma1 protein, rat; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; C490547:MAP1A protein, mouse; C490546:Map1a protein, rat; D008869:Microtubule-Associated Proteins; D015221:Potassium Channels; D011993:Recombinant Fusion Proteins; D005982:Glutathione Transferase