Histidine Rich Calcium Binding Protein (HRC)

This gene encodes a luminal sarcoplasmic reticulum protein identified by its ability to bind low-density lipoprotein with high affinity. The protein interacts with the cytoplasmic domain of triadin, the main transmembrane protein of the junctional sarcoplasmic reticulum (SR) of skeletal muscle. The protein functions in the regulation of releasable calcium into the SR.

This sequence bound MEF2 in a mobility shift assay, and it was necessary and sufficient to direct expression of a reporter gene during embryonic development in mouse cardiac, skeletal, and vascular smooth muscle cells. The enhancer sequence lacks an SRF-binding site and was not activated by SRF. The HRC enhancer is unusual in that it is an MEF2-dependent and SRF-independent transcriptional target in smooth muscle cells.