SNARE protein regulation of cardiac potassium channels and atrial natriuretic factor secretion

Coordinated cardiac ion channel gating is fundamental for generation of action potential and excitability throughout the myocardium. The interaction of pore-forming ion channels with auxiliary subunits can regulate surface expression, localization and anchoring of these channels to plasma membrane. SNARE (soluble N-ethylmaleimide sensitive factors attachment protein or SNAP receptor) proteins mediate the targeting, docking, and fusion of intracellular vesicles for exocytotic release of neurotransmitters and hormones. In secretory neurons and neuroendocrine cells, some voltage-gated channels are physically coupled with SNARE proteins, resulting in alterations in channel gating and trafficking. Coupling of SNARE proteins to membrane ion channels is however not unique to secretory cells. We have demonstrated the expression of SNARE proteins in rodent myocardial tissue, and more importantly, functional interaction of SNARE proteins with cardiac K_ATP and K_v (K_v1.2, K_v2.1, K_v4.2, K_v4.3, and K_v11.1) channels. SNARE proteins, therefore, have similar fundamental functions in ion channel trafficking and regulation per se, independent of secretion. We now review the body of work of SNARE protein regulation on membrane ion channels in the heart.