Reticulocalbin 1 (RCN1)

Reticulocalbin 1 is a calcium-binding protein located in the lumen of the ER. The protein contains 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 comparison to mouse reticulocalbin, is consistent with a possible biochemical function besides that of calcium binding.The predicted 331-amino acid human RCN1 protein is 95% identical to the mouse Rcn protein. RCN1 contains a leader peptide, 6 EF-hand calcium-binding motifs, and a C-terminal HDEL sequence, which serves as an ER retention signal. By Western blot analysis of human mammalian cell extracts, antibodies against Rcn recognized 44- and 46-kD proteins. Northern blot analysis revealed that RCN1 was expressed as a 2.4-kb transcript in all tissues tested.