The amino-acid sequence of the alpha subunit in bovine brain S-100a protein.

The brain specific S-100 protein is a mixture of two components S-100a and S-100b with a subunit composition alpha beta or beta 2 respectively. The amino acid sequence of the beta subunit has been previously determined. This paper presents the sequence of the alpha subunit in the S-100a protein. The alpha subunit consists of 93 amino-acid residues and has a relative molecular mass of 10,400. The sequence shows extensive homology (58%) with that of the beta-subunit and shares an apparent calcium binding site in the C-terminal half of the molecule, suggesting a close evolutionary relationship between these subunits.