Determination of the amino acid sequence of troponon C from rabbit skeletal muscle.

The complete amino acid sequence of rabbit skeletal muscle troponin C (TnC) was determined from studies on overlapping peptides isolated from cyanogen bromide and tryptic digests. TnC was found to be a single polypeptide chain of 159 amino acid residues, including 2 residues of tyrosine and 1 each of cysteine, histidine, and proline. The amino end is acetylated, the calculated net charge at pH 7.0 is -29, and the calculated molecular weight is 17,965. There was no evidence for heterogeneity in the sequence. The previously proposed four apparent Ca2+ binding sites are located at residues 27 to 38, 63 to 74, 103 to 114, and 139 to 150.