The Role of Calcium-activated Potassium Channel in Mitochondria-Associated ER Membrane and Its Functional Link to Cell Survival and Death

The process of apoptosis is not only regulated by molecular gens but it is also regulated by cellular ionic homeostasis especially K+ homeostasis in the cell. In the past decade, molecular mechanisms of ionic regulation of apoptosis have been extensively investigated. The ionic mechanism of apoptosis are involves Ca2+ influx and accumulation of intracellular Ca2+ is convincing evidence to excessive K+ efflux resulting in early steps in apoptosis. The BK channels play a critical role in mediating the K+ efflux linked with apoptotic cell shrinkage. Mitochondria-associated ER membranes (MAMs) control Ca2+ influx between ER and mitochondria. The BKα subunits are localized in the inner mitochondrial and ER membrane and directly interact with other BK channel associated proteins (BKAPs) like, IP3R-1, calreticulin at the ER face of the MAMs, and the molecular chaperone grp78, which bridges the IP3R-1 with voltage-dependent anion channel (VDAC-1) of the outer mitochondrial membrane (OMM). The present chapter clearly depicts that how BK channels are associated with BKAPs and how they are involved in apoptosis through regulation of K+ efflux