Calreticulin (CALR) is expressed in the endoplasmic reticulum. The gene encoding it is localized on human chromosome 19p13.13.

Human calreticulin has been used in a study to determine the effects of uncoupling protein 4 (UCP4) on the expression of proteins in the store-operated Ca²⁺ entry pathway.

Calreticulin is involved in regulation of intracellular Ca²⁺ homoeostasis and ER Ca²⁺ capacity. It constitutes together with calnexin and ERp57 the ′calreticulin/calnexin cycle′ that is responsible for folding and quality control of newly synthesized glycoproteins. Calreticulin has been implicated to play a role in many biological systems, including functions inside and outside the ER, indicating that the protein is a multi-process molecule. Recently, Calreticulin was shown to enhance the merger of macrophages and tumor cells, increasing phagocytosis.

Solution in 55 mM TRIS-HCl, pH 8.2, containing 150 mM NaCl.

Human calreticulin (aa18-417) is fused at the C-terminus to a His-tag.