This gene encodes a luminal sarcoplasmic reticulum protein identified by its ability to bind low-density lipoprotein with high affinity. The protein interacts with the cytoplasmic domain of triadin, the main transmembrane protein of the junctional sarcoplasmic reticulum (SR) of skeletal muscle. The protein functions in the regulation of releasable calcium into the SR. [provided by RefSeq, Sep 2008].