RCN1 is a calcium-binding protein which binds calcium and controls calcium-dependent activities in the endoplasmic reticulum lumen or post-ER compartment. RCN1 withholds six conserved regions with similarity to a high affinity Ca（+2）-binding motif， the EF-hand.
High conservation of amino acid residues outside of these motifs， in relation to mouse reticulocalbin， is consistent with a biochemical function further to that of calcium binding. In human endothelial and prostate cancer cell lines RCN1 protein is localized to the plasma membrane.
