Calreticulin 3, also known as CALR3, is a member of the calreticulin (CRT) family. It is calcium-binding chaperones that are localized to the endoplasmic reticulum or sarcoplasmic reticulum in eukaryotes. CALR3 assists in the calreticulin/calnexin cycle, where it is involved in protein-folding, oligomeric assembly and quality control in the ER. With specific expression in testis, CALR3 has been implicated as a cancer-testis antigen due to its frequent expression in various cancers. Recombinant human CALR3 protein was expressed in E.coli.