Calumenin, also known as calumenin isoform a, which is a multiple EF-hand calcium-binding protein located in endoplasmic reticulum (ER) and sarcoplasmic reticulum (SR) of mammalian tissues. This protein binds 7 calcium ions with a low affinity and is involved in such ER functions as protein folding and sorting. Recombinant human Calumenin protein was expressed in E. coli and purified by using conventional chromatography.