RyR1 (D4E1) Rabbit mAb #8153

Ryanodine receptors (RyRs) are large (>500 kDa), intracellular calcium channels found in the sarcoplasmic/endoplasmic reticulum membrane and are responsible for the release of Ca²⁺ from intracellular stores in excitable cells, such as muscle and neurons. RyRs exist as three mammalian isoforms (RyR1-3), all of which form homotetramers regulated by phosphorylation and/or direct or indirect interaction with a variety of proteins (L-type calcium channels, PKA, FKBP12/12.6, CaMKII, calmodulin, calsequestrin, junctin, and triadin) and ions (Mg²⁺ and Ca²⁺). Regulation of the RyR channel by protein modulators occurs within the large cytoplasmic domain, whereas the carboxy-terminal portion of the protein forms the ion-binding and conducting pore (1,2). RyR1 and RyR2 are predominantly expressed in skeletal and cardiac muscle, respectively, where they localize exclusively to the sarcoplasmic reticulum (SR) and facilitate calcium-mediated communication between transverse-tubules and sarcoplasmic reticulum. Contraction of skeletal muscle is triggered by release of calcium ions from the SR following depolarization of T-tubules. Research studies have shown that defects in RyR1 are the cause of malignant hyperthermia susceptibility type 1 (MHS1), central core disease of muscle (CCD), multiminicore disease with external ophthalmoplegia, and congenital myopathy with fiber-type disproportion (CFTD), each of which is manifested by defects in muscle function, metabolism, and development (2). Investigators have shown that defects in RyR2 are the cause of familial arrhythmogenic right ventricular dysplasia type 2 (ARVD2) and catecholaminergic polymorphic ventricular tachycardia type 1 (CPVT1), both of which are implicated in sudden death syndromes as a result of electrical instability and degeneration of the ventricular myocardium or stress-induced ventricular tachycardia (2). Despite low levels of expression in skeletal and smooth muscle, RyR3 is the dominant isoform in neuronal cells (hippocampal neurons, thalamus, Purkinje cells) and has been implicated in synaptic plasticity, dendritic spine remodeling, and spatial memory formation (3). The role of RyR3 in neuronal function has been substantiated by mice lacking RyR3, which demonstrate normal motor function, but possess numerous behavioral and social defects (4).