Regucalcin (RGN)

Regucalcin (RGN), also known as senescence marker protein 30 (SMP30), is a highly conserved calcium-binding protein primarily expressed in the liver, kidney, and other tissues, where it regulates intracellular calcium homeostasis and modulates a range of Ca^2+^-dependent signaling enzymes, including kinases and phosphatases[2][3][4]. Unlike classic calcium-binding proteins, it does not contain the EF-hand motif. In addition to its role in Ca^2+^ signaling, regucalcin functions as a lactonase and gluconolactonase, involved in the catabolism of carbohydrate lactones and, in nonprimate mammals, vitamin C biosynthesis[1][2]. Its expression decreases with age, and altered levels are implicated in multiple disorders, including cancer, neurodegenerative and cardiovascular diseases, and age-associated frailty, making it a potential biomarker for disease progression[2][4]. Regucalcin is not currently a target of approved therapeutic drugs, but its multifaceted roles in cell survival, oxidative stress regulation, and apoptosis make it a significant subject of biomedical research.

Other names

Senescence marker protein 30SMP30RCGluconolactonaseGNLHEL-S-41Epididymis secretory protein Li 41SMP-30

Hydrolysis of lactones and related substrates (as a lactonase and gluconolactonase)[1] - Regulation of calcium pump enzymes, affecting Ca^2+^ flux across membranes[2][3][4]