Junctin - the quiet achiever.

摘要

Recent advances in understanding skeletal and cardiac muscle function have evolved with recognition of the active role played by the intracellular sarcoplasmic reticulum (SR) Ca~2+ store in contraction. The key proteins in this store are the Ca~2+ binding protein calsequestrin (CSQ), the ryanodine receptor (RyR) Ca~2+ release channel and triadin and junctin (Beard et al. 2004). The CSQ-triadin-junctin-RyR complex (Fig. 1) in the SR lumen forms a 'Ca~2+ transduction machine' that is central to EC coupling and to normal muscle development. Other proteins in the lumen of the SR, including the histidine rich calcium binding protein (HRC) (Suk et al. 1999), JP-45 (Anderson et al. 2003) and SRP-27 (Bleunven et al. 2008), must also contribute to control of SR intraluminal Ca~2+ load, but the precise nature of their role remains undetermined. JP-45 in particular is ideally placed to communicate