title: F-actin-binding synthetic heptapeptide having the amino acid sequence around the SH1 cysteinyl residue of myosin.
abstract: The heptapeptide Ile-Arg-Ile-Cys-Arg-Lys-Gly-ethyl ester, having the amino acid sequence around the SH1 of myosin heavy chain, was coprecipitated with F-actin after ultracentrifugation. The heptapeptide inhibited the formation of acto-S-1 rigor complex by competing with S-1 for actin. Assuming a simple competitive inhibition, the dissociation constant of acto-heptapeptide complex was evaluated as 0.23 mM. An N-terminal tripeptide derivative from the heptapeptide Ile-Arg-Ile-methyl ester also formed a complex with F-actin with a dissociation constant of 1.1 mM. However, the other piece, Cys-Arg-Lys-Gly-ethyl ester, and a tetrapeptide, Val-Leu-Glu-Gly-ethyl ester, having the sequence adjacent to the N-terminal of the heptapeptide, scarcely bound with F-actin. These results suggest that part of the actin-binding site of myosin heavy chain around SH1 (Katoh, T., Katoh, H., and Morita, F. (1985) J. Biol. Chem. 260, 6723-6727) has the sequence of Ile-Arg-Ile and it is located adjacent to SH1 on its N-terminal side.
mesh_terms: D000199:Actins / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000032:analysis*; D003545:Cysteine; D007700:Kinetics; D008840:Microfilament Proteins / Q000032:analysis*; D015879:Myosin Subfragments; D009218:Myosins / Q000032:analysis*; D009842:Oligopeptides / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis*; D011817:Rabbits; D014461:Ultracentrifugation
chemical_list: D000199:Actins; D002352:Carrier Proteins; C034037:F-actin-binding proteins; D008840:Microfilament Proteins; D015879:Myosin Subfragments; D009842:Oligopeptides; D010446:Peptide Fragments; C053435:isoleucyl-arginyl-isoleucyl-cysteinyl-arginyl-lysyl-glycine ethyl ester; D000255:Adenosine Triphosphate; D009218:Myosins; D003545:Cysteine