Ryanodine receptors in the central nervous system.

Ryanodine receptor (RyR) is a calcium release channel protein on the intracellular Ca(2+)-store. While inositol 1,4,5-trisphosphate receptor (IP3R), another intracellular calcium release channel protein, is mainly found in non-muscle cells, such as neurons and hepatocytes, and smooth muscles, RyR is the Ca(2+)-release channel protein in skeletal and cardiac muscles. At least three genetically distinct isoforms of RyR are identified: isoform proteins Ryr1, Ryr2, and Ryr3 expressed by ryr1, ryr2 and ryr3, respectively. In the central nervous system where IP3R is much more abundant than RyR, the main isoform of RyR is Ryr2, which is specific to the cardiac ventricular muscle. Recently, ryr3 was detected in specific regions of the brain. In this paper, the heterogeneous distribution and localization of RyR isoforms in the brain are summarized. The discussion extends into their putative functions, especially potential involvement in neuronal plasticity.