Calreticulin (CALR)

Calreticulin is a protein that binds Ca2 ions (a second messenger molecule in signal transduction), rendering it inactive. The Ca2 is bound with low affinity, but high capacity, and can be released on a signal. Calreticulin is located in storage compartments associated with the endoplasmic reticulum.

Calreticulin is also known as calregulin, CRP55, CaBP3 and calsequestrin-like protein. The term "Mobilferrin" is considered to be the same as calreticulin by some sources.Calreticulin binds to misfolded proteins and prevents them from being exported from the Endoplasmic reticulum to the Golgi apparatus.A similar quality control chaperone, calnexin, performs the same service for soluble proteins as does calreticulin.