Calcyphosine （CAPS） is a calcium-binding protein containing four EF-hand domains. CAPS protein was originally identified as thyroid protein p24 which is found in a number of epithelium and in some cells of the central nervous system. CAPS may have a role in the regulation of ion transport. In the thyroid follicular cells， CAPS is synthesized and phosphorylated in response to stimulation by thyrotropin and cAMP agonists.
