The CASQ2 gene encodes a calcium binding protein called calsequestrin 2 that stores calcium, which is vital for the functionality of muscles.  This protein is found in the sarcoplasmic reticulum in cardiac and slow skeletal muscle cells.  Within myocytes, the calsequestrin 2 protein acts as a storage center for calcium ions in the sarcoplasmic reticulum; most of these ions bind by clusters of acidic residues at the protein surface.  The Calsequestrin 2 protein also regulates the release of lumenal Ca(2+) through the RYR2 channel; this plays an essential role in triggering muscle contractions including these involved in the heart rhythm.  Defects in this protein have been associated with catecholaminergic polymorphic ventricular tachycardia type 2, a disease characterized by adrenergically induced ventricular tachycardia (VT) that may lead to sudden death due to cardiac arrest.

The CASQ2 gene is located on chromosome 1p13.1 and contains 11 exons spanning approximately 69 kb in the genomic DNA.  The encoded protein comprises 399 amino acids with a molecular weight of 46 kDa.  Thirteen mutations in the CASQ2 gene have been identified in patients with an autosomal recessive form of catecholaminergic polymorphic ventricular tachycardia.