Calumenin belongs to the CREC family. It contains 6 EF-hand domains. Calumenin is expressed in skeletal muscle (at protein level). Calumenin interacts with GGCX and RYR1 in the presence of calcium ions, but not in the presence of EDTA. Calumenin is Involved in regulation of vitamin K-dependent carboxylation of multiple N-terminal glutamate residues. It seems to inhibit gamma-carboxylase GGCX. Calumenin also binds 7 calcium ions with a low affinity and may modulate calcium release from the sarcoplasmic reticulum.