CHERP (calcium homeostasis endoplasmic reticulum protein) is a ubiquitously expressed integral sarco/endoplasmic reticulum (SR/ER) membrane protein. CHERP protein consist of 916 amino acid in humans and its structure containing a Pro-rich region and a segment of Arg-Ser dipeptide repeats (an RS domain) near the C terminus, and an RNA recognition motifs (RRMs)^1-3.

CHERP acts as a regulator of both major families of endoplasmic reticulum Ca²⁺ channels, inositol 1,4,5-trisphosphate receptors (IP₃Rs) and ryanodine receptors (RyRs). CHERP is responsible for the regulation of intracellular Ca²⁺ mobilization in human cells and is involved in neuroblastoma cell proliferation, apoptosis and tumorigenicity^1,2.

CHERP co-localizes with IP₃ receptors throughout the cytoplasmic and perinuclear regions in human erythroleukemia cells and in Jurkat cells. CHERP is also detected in the nucleoplasm with prominent accumulation at nuclear speckles^1,2. CHERP co-localizes with endogenous ryanodine receptor type 1 (RyR1) in the sarcoplasmic reticulum of rat soleus muscle. Studies of CHERP knockdown reveal decreased intracellular Ca²⁺ mobilization, cell growth and proliferation^2,3.