Neurocalcin: a novel calcium-binding protein from bovine brain.

A novel calcium-binding protein (molecular weight 23,000-24,000, pI 5.3-5.5), which we term neurocalcin, was identified in bovine brain. Using calcium-dependent drug affinity chromatography ((S)-P-(2-aminoethyloxy)-N-[2-(4-benzyloxycarbonylpiperazinyl++ +)-1-(P- methoxybenzyl)ethyl]-N-methylbenzene-sulfonamide dihydrochloride, W-77, -coupled Sepharose 6B), we purified neurocalcin from bovine brain. The partial amino acid sequence of neurocalcin revealed it to be an as yet unidentified protein with three putative calcium binding sites (EF-hands). Further purification and sequence analysis demonstrated the presence of four isoprotein forms designated alpha, beta, gamma 1, and gamma 2. When the 165 sequenced residues of neurocalcin beta are compared with sequences of other proteins, neurocalcin beta has a 38.2% sequence homology with visinin and 45.5% with recoverin (Yamagata, K., Goto, K., Kuo, C.-H., Kondo, H., and Miki, N. (1990) Neuron 2, 469-476; Dizhoor, A. M., Ray, S., Kumar, S., Niemi, G., Spencer, M., Brolley, D., Walsh, K. A., Philipov, P. P., Hurley, J. B., and Stryer, L. (1991) Science 251, 915-918). Both visinin and recoverin are expressed specifically in retinal photoreceptors and are not found in brain. Unlike visinin and recoverin, neurocalcin is purified not only from retina but also from bovine brain. Our results suggest that neurocalcin is a recoverin-like protein expressed in bovine brain.