BK_Ca channels as physiological regulators: a focused review

Figures & data

Figure 1 Signaling pathway downstream of BK_Ca channels involved in the regulation of various physiological processes.

Notes: BK_Ca channels mediate membrane potential changes that regulate Ca²⁺ channels. Intracellular stores of Ca²⁺ released to the cytosol via the ryanodine receptor of the sarcoplasmic reticulum activate BK_Ca channels. An increase in the intracellular Ca²⁺ levels and an increase in the elimination of K⁺ regulate several physiological processes, including vascular tone, neurotransmission, intraocular pressure, and urinary bladder tone.
Abbreviations: BKCa, large conductance calcium-activated potassium channels; PM, plasma membrane; RyR, ryanodine receptor; IP₃R, inositol 1,4,5 triphosphate receptor; SERCA, sarcoendoplasmic reticulum ATPase; SR, sarcoplasmic reticulum; NCX, sodium–calcium exchanger; TRP, transient receptor potential channel; MLCK, myosin light chain kinase.

Figure 2 Structure and regulation of BK_Ca channel.

Notes: Schematic diagram representing the threading of BK_Ca channel subunits (α and β) through the plasma membrane. Agonist-mediated stimulation leads to the activation of PKA, PKC, and PKG and to the phosphorylation of the subunits, an important mechanism through which BK_Ca channel modulates physiological process. Cytoplasmic C-terminal domain consists of four primary Ca²⁺ binding sites, called the “Ca²⁺ bowl”. The domains sensitive to voltage, Ca²⁺, and stretch are also depicted.
Abbreviations: BKCa, large conductance calcium-activated potassium channels; PKA, protein kinase A; PKG, protein kinase G; EM, extracellular side of plasma membrane; IM, intracellular side of plasma membrane; STREX, hormonal stress axis exon; PKC, protein kinase C; p, phosphate binding site.