Functional effects of cytoskeletal components on the lateral movement of individual BKCa channels expressed in live COS-7 cell membrane.

The lateral diffusion of BK(Ca) channels was previously shown to be highly 'confined' in the COS-7 cell membrane. Here we report that the diffusion coefficient and the confinement area of BK(Ca) channel were significantly increased by the treatment of latrunculin A, an actin-depolymerizing agent, but not by microtubule disruption. Site-directed mutational analyses further demonstrated that a single leucine residue in the C-terminal actin-binding motif was critical for the aforementioned effects of latrunculin A. We conclude that some BK(Ca) channels are directly associated with actin filaments and their lateral mobility can be restricted by the cytoskeletal components.