The large conductance calcium-activated K+ channel interacts with the small GTPase Rab11b

The transduction of sound by the receptor or hair cells of the cochlea leads to the activation of ion channels found in the basal and lateral regions of these cells. Thus, the processing of these transduced signals to the central nervous system is tied to the regulation of baso-lateral ion channels. The large conductance calcium-activated potassium or BK channel was revealed to interact with the small GTPase, Rab11b, which is one of many Rabs found in various endosomal pathways. Immunoelectron microscopy showed the colocalization of these two proteins in receptor cells and auditory neurons. Using Chinese hamster ovary cells as a heterologous expression system, Rab11b increased or decreased BK expression, depending on the overexpression or RNAi knockdown of Rab, respectively. Additional mutation analyses, using a yeast two-hybrid assay, suggested that this GTPase moderately interacts within a region of BK exclusive of the N- or C-terminal tails. These data suggest that this small GTPase regulates BK in a slow recycling process through the endocytic compartment and to the plasmalemma. (C) 2012 Elsevier Inc. All rights reserved.