Hippocalcin: a calcium-binding protein of the EF-hand superfamily dominantly expressed in the hippocampus

Abstract

Hippocalcin is a recently identified Ca(2+)-binding protein with three EF-hand structures, dominantly expressed in the hippocampal pyramidal layer. The complete amino acid sequence of hippocalcin deduced from the cDNA is composed of 195 residues, has a calculated molecular mass of 22,574 daltons, and has a striking sequence homology to those of visinin, recoverin, S-modulin, neurocalcins and neural visinin-like proteins. Hippocalcin binds 3 mol of Ca2+ per mol of protein at submicromolar Ca2+ levels, and associates the plasma membrane in a Ca(2+)-dependent manner. Hippocalcin is myristoylated at its NH2-terminal glycine residue, and this modification is a key event in terms of its membrane-association property.