Amino acid sequence of the regulatory light chain of clam foot muscle myosin.

The amino acid sequence of the regulatory light chain of foot muscle myosin from surf-clam (Spisula sachalinensis) was determined by conventional methods. It was: xS-D-D-K-K-A-K-A-A-T-S-S-V-L-T-K-F-T-Q-N-Q-I-Q-E-M-K-E-A-F-T-M-I-D-Q-N-R -D-G-L- I-D-V-S-D-L-K-E-M-Y-S-N-L-G-T-A-P-Q-D-S-V-L-Q-A-M-V-K-E-A-P-Q-M-N-F-T-G- F-L-S-L- F-S-E-K-M-S-G-T-D-P-E-E-T-L-R-N-A-F-Q-M-F-D-S-D-N-T-G-Y-I-P-E-E-Y-M-K-D- L- L-E-N-M-G-D-N-F-S-K-D-E-V-R-Q-T-W-K-E-A-P-I-A-G-G-K-V-D-Y-N-A-F-V-S-K-I- K- G-K-E-Q-D-D-A. The alpha-amino group of the light chain was blocked, and a typical calcium binding structure was recognized at the 33rd to 44th residues, as in other myosin regulatory light chains. The sequences of regulatory light chains from various muscle myosins were arranged according to the well known four-domain structure, and structural homologies were obtained for each of the domains. Based on the homologies, the relationships between the structure, function, and molecular evolution were discussed.