Calreticulin, a multifunctional Ca2+ binding chaperone of the endoplasmic reticulum

Calreticulin is a ubiquitous endoplasmic reticulum Ca 2+ binding chaperone. The protein has been implicated in a variety of diverse functions. Calreticulin is a lectin-like chaperone and, together with calnexin, it plays an important role in quality control during protein synthesis, folding, and posttranslational modification. Calreticulin binds Ca 2+ and affects cellular Ca 2+ homeostasis. The protein increases the Ca 2+ storage capacity of the endoplasmic reticulum and modulates the function of endoplasmic reticulum Ca 2+ -ATPase. Calreticulin also plays a role in the control of cell adhesion and steroid-sensitive gene expression. Recently, the protein has been identified and characterized in higher plants but its precise role in plant cells awaits further investigation.Key words: calreticulin, endoplasmic reticulum, chaperone, Ca 2+ binding protein.