Regulation of the ryanodine receptor calcium release channel: a molecular complex system.
Skeletal muscle contraction is regulated by Ca(2+) released from the sarcoplasmic reticulum (SR). The Ca(2+) release channel in the SR has been identified as the ryanodine receptor (RyR). Recently, it was found that the RyR is a large transmembrane protein that is regulated by many intrinsic factors. In this review, we mainly summarize our experimental results. We will first show that calsequestrin and the DIDS-binding 30-kDa protein work as intrinsic factors and regulate the RyR Ca(2+) release channel. Next, the DIDS-binding 30-kDa protein was identified as the ADT/ATP translocase (AAT) present in mitochondria, based on a cDNA analysis. This result shows that AAT is bifunctional and works as a transporter protein in mitochondria and as a regulator of Ca(2+) release in the SR. From these results, we propose a model in which calsequestrin, the DIDS-binding 30-kDa protein, and junctin form a ternary complex that regulates the RyR Ca(2+) release channel through interactions with triadin.
Kasai
M
M
Division of Biophysical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan. kasai@bpe.es.osaka-u.ac.jp
Kawasaki
T
T
Yamaguchi
N
N