Ryanodine receptors, voltage-gated calcium channels and their relationship with protein kinase A

Short title: Ryanodine receptors, voltage-gated calcium channels and PKA Abstract We present the review of the data from the literature about relationship between ryanodine receptors and voltage-gated calcium channels in myocardium, and also how both of them are related to protein kinase A. Ryanodine receptors, which have three subtypes (RyR1-3), are located on the membrane of sarcoplasmic reticulum. Different subtypes of voltage gated calcium channels interact with ryanodine receptors in skeletal and cardiac muscle tissue. The mechanism of excitation-contraction coupling is therefore different in skeletal and cardiac muscle. However, in both tissues ryanodine receptors and voltage-gated calcium channels seem to be physically connected. FK-506 binding proteins (FKBPs) are bound to ryanodine receptors, thus allowing for their concerted activity, called coupled gating. Activity of both ryanodine receptors and voltage gated calcium channels is positively regulated by protein kinase A. These effects are, therefore, components of the mechanism of sympathetic stimulation of myocytes. The specificity of this enzyme's targeting is achieved by using different A kinase adapting proteins. Different diseases are related to inborn or acquired changes in ryanodine receptor activity in cardiac myocytes. Mutations in cardiac ryanodine receptor gene can cause catecholamine provoked ventricular tachycardia. Changes in phosphorylation state of ryanodine receptors can provide a credible explanation for development of heart failure. The restoration of their normal level of phosphorylation could explain the positive effect of beta-blockers in treatment of this disease. In conclusion, molecular interactions of ryanodine receptors and voltage-gated calcium channels with PKA have significant physiological role. However, their defects and alterations can result in serious disturbances.