Mutations in CAV3 cause LQT syndrome 9 (LQT9). A previously reported LQT9 patient had prominent U waves on ECG, a feature that has been correlated with Kir2.1 loss of function.
View Article and Find Full Text PDFJ Biomed Biotechnol
March 2012
The fidelity of excitation-contraction (EC) coupling in ventricular myocytes is remarkable, with each action potential evoking a [Ca²⁺](i) transient. The prevalent model is that the consistency in EC coupling in ventricular myocytes is due to the formation of fixed, tight junctions between the sarcoplasmic reticulum (SR) and the sarcolemma where Ca²⁺ release is activated. Here, we tested the hypothesis that the SR is a structurally inert organelle in ventricular myocytes.
View Article and Find Full Text PDFA-kinase anchoring proteins (AKAPs) tether the cAMP-dependent protein kinase (PKA) to intracellular sites where they preferentially phosphorylate target substrates. Most AKAPs exhibit nanomolar affinity for the regulatory (RII) subunit of the type II PKA holoenzyme, whereas dual-specificity anchoring proteins also bind the type I (RI) regulatory subunit of PKA with 10-100-fold lower affinity. A range of cellular, biochemical, biophysical, and genetic approaches comprehensively establish that sphingosine kinase interacting protein (SKIP) is a truly type I-specific AKAP.
View Article and Find Full Text PDFBackground: KCNJ2 encodes Kir2.1, a pore-forming subunit of the cardiac inward rectifier current, I(K1). KCNJ2 mutations are associated with Andersen-Tawil syndrome and catecholaminergic polymorphic ventricular tachycardia.
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