The ryanodine receptor family of intracellular calcium release channels

Molecular studies have provided data on the nature and function of the intracellular calcium release channels. Two distinct classes of channels that mediate release of calcium from intracellular stores have been identified. The first is sensitive to InsP3 and is referred to as the InsP3 receptor family and the second is sensitive to a nonphysiological ligand, the plant alkaloid ryanodine (Ry), hence the name Ry receptors (RyR). These two classes of calcium release channels have general structural similarities: the active channels have a tetrameric structure in which four subunits assemble to form the functional channel. This chapter focuses only on the RyRs. Preset knowledge about the contribution of RyR to calcium signaling is extending from its original field of interest, namely, muscle physiology, to several other areas. Along with their fundamental role in regulating skeletal and cardiac muscle contraction, a functional involvement of RyRs in different central nervous system (CNS) activities, such as long-term potentiation (LTP) and long-term depression (LTD) has been proposed. Research suggests that these channels are present and functional in many other cell types, in addition to muscle and neuron cells. © 1995 Academic Press Inc.