Calumenin also known as CALU is a member of the CREC, EF-hand protein family and is characterized by six calcium-binding EF-hand motifs. Calumenin is primarily located in the lumen of the endoplasmic reticulum and Golgi apparatus, where Calumenin plays a crucial role in calcium homeostasis and protein folding. Calumenin′s localization facilitates proper functioning of the secretory pathway, ensuring proteins are correctly modified and folded before transport to their final destinations. Calumenin interacts with serum amyloid P component (SAP) in the presence of calcium, suggesting a potential role in immunological defense and pathological processes associated with amyloidosis.