Regucalcin （RGN） is a member of the SMP-30/CGR1 family. Regucalcin is a Ca （2+）-binding protein which does not contain EF-hand motif of Ca （2+）-binding domain. RGN has a critical role in the keep of intracellular Ca2+ homeostasis due to activating of Ca2+ pump enzymes in the plasma membrane （basolateral membrane）， microsomes （endoplasmic reticulum） and mitochondria of many cells. Moreover， RGN plays a multifunctional role in the regulation of cell functions in the liver， kidney cortex， heart and brain and a suppressor protein for cell signaling systems in many cell types.
