Association of plasma membrane BKCachannels with BK‐β subunits shapes their biophysical properties and physiological roles; however, functional modulation of the mitochondrial BKCachannel (mitoBKCa) by BK‐β subunits is not established. MitoBKCa‐α and the regulatory BK‐β1 subunit associate in mouse cardiac mitochondria. A large fraction of mitoBKCadisplay properties similar to that of plasma membrane BKCawhen associated with BK‐β1 (left‐shifted voltage dependence of activation, In BK‐β1 knockout mice, cardiac mitoBKCadisplayed a low Co‐expression of BKCawith the BK‐β1 subunit in HeLa cells doubled the density of BKCain mitochondria. The present study supports the view that the cardiac mitoBKCachannel is functionally modulated by the BK‐β1 subunit; proper targeting and activation of mitoBKCashapes mitochondrial Ca2+handling.
Association of the plasma membrane BKCachannel with auxiliary BK‐β1–4 subunits profoundly affects the regulatory mechanisms and physiological processes in which this channel participates. However, functional association of mitochondrial BK (mitoBKCa) with regulatory subunits is unknown. We report that mitoBKCafunctionally associates with its regulatory subunit BK‐β1 in adult rodent cardiomyocytes. Cardiac mitoBKCais a calcium‐ and voltage‐activated channel that is sensitive to paxilline with a large conductance for K+of 300 pS. Additionally, mitoBKCadisplays a high open probability (