New molecular components supporting ryanodine receptor-mediated Ca(2+) release: roles of junctophilin and TRIC channel in embryonic cardiomyocytes.
Ca(2+) mobilization from intracellular stores is mediated by Ca(2+) release channels, designated ryanodine and IP(3) receptors, and directly regulates important cellular reactions including muscle contraction, endo/exocrine secretion, and neural excitability. In order to function as an intracellular store, the endo/sarcoplasmic reticulum is equipped with cooperative Ca(2+) uptake, storage and release machineries, comprising synergic collaborations among integral-membrane, cytoplasmic and luminal proteins. Our recent studies have demonstrated that junctophilins form junctional membrane complexes between the plasma membrane and the endo/sarcoplasmic reticulum in excitable cells, and that TRIC (trimeric intracellular cation) channels act as novel monovalent cation-specific channels on intracellular membrane systems. Knockout mice have provided evidence that both junctophilins and TRIC channels support efficient ryanodine receptor-mediated Ca(2+) release in muscle cells. This review focuses on cardiac Ca(2+) release by discussing pathological defects of mutant cardiomyocytes lacking ryanodine receptors, junctophilins, or TRIC channels.
Yamazaki
Daiju
D
Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.
Yamazaki
Tetsuo
T
Takeshima
Hiroshi
H
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004622:Embryo, Mammalian / Q000166:cytology; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D007473:Ion Channels / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D032383:Myocytes, Cardiac / Q000378:metabolism*; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics / Q000502:physiology*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
D007473:Ion Channels; D008565:Membrane Proteins; D019837:Ryanodine Receptor Calcium Release Channel; C522221:TRIC-A protein, mouse; C522222:TRIC-B protein, mouse; C412507:junctophilin; D002118:Calcium