Involved in regulation of vitamin K-dependent carboxylation of multiple N-terminal glutamate residues. Seems to inhibit gamma-carboxylase GGCX. Binds 7 calcium ions with a low affinity (By similarity). May modulate calcium release from the sarcoplasmic reticulum. Interacts with GGCX (By similarity). Interacts with RYR1 in the presence of calcium ions, but not in the presence of EDTA. Detected in skeletal muscle (at protein level). Belongs to the CREC family. PubMed:16527250 attributed the differences between their clones to the existence of two separate genes. This seems rather unlikely, considering that the cDNAs are 100% identical outside of this clearly delimited zone.