Tanaka H, Ojima T, Nishita K
Department of Marine Bioresources Chemistry, Faculty of Fisheries, Hokkaido University, Hakodate, Hokkaido, 041-8611, Japan.
J Biochem. 1998 Aug;124(2):304-10. doi: 10.1093/oxfordjournals.jbchem.a022112.
The complete amino acid sequence of Akazara scallop, Chlamys nipponensis akazara, troponin-I was determined by automated Edman degradation. It is composed of 292 amino acid residues with a blocked N-terminus. The Mr is calculated to be 34,678, about 14,000 larger than that of vertebrate skeletal troponin-I but significantly smaller than the 52,000 that had been estimated by SDS-polyacrylamide gel electrophoresis. The homologous sequence to vertebrate and arthropoda troponin-Is is found in the C-terminal region. In particular, the sequence of the regions essential for binding to actin and troponin-C is highly conserved. On the other hand, Akazara scallop troponin-I has 100-133 extra residues at the N-terminus compared with vertebrate troponin-I. This extra region is rich in Glu and Arg and has a unique sequence, that shows in part a high sequence homology with the tropomyosin-binding site of troponin-T and caldesmon.
