A heptapeptide analog of the actin-binding S-site on the myosin head induced polymerization of G-actin to F-actin with a half-maximal concentration of about 110 microM.
Does a heptapeptide analog of the myosin head S-site promote polymerization of G-actin to F-actin?
A heptapeptide analog of the myosin head S-site promotes the polymerization of G-actin to F-actin, suggesting that the acceleration of actin polymerization by the myosin head may be due to binding at this S-site.
Polymerization of G-actin to F-actin was indicated by an increase in light-scattering intensity after the addition of a heptapeptide (Ile-Arg-Ile-Cys(MT)-Arg-Lys-Gly-OEt), an analog of the actin-binding S-site on S-1 heavy chain. The half-maximal concentration of the heptapeptide which induced an increase in the light-scattering intensity at 25 degrees C was about 110 microM, which was in the range of the dissociation constant of this peptide with F-actin. The polymerization of G-actin to F-actin by binding of the heptapeptide was further demonstrated by ultracentrifugal separation, Pi liberation, and electron microscopy. The polymerization of G-actin was induced only by the heptapeptide, but not by fragments of the heptapeptide. The well known acceleration of polymerization of G-actin by the myosin head may be due to the binding of G-actin with the S-site on the myosin head.
Eto et al. (Sun,) reported a other. Heptapeptide (Ile-Arg-Ile-Cys(MT)-Arg-Lys-Gly-OEt) vs. Fragments of the heptapeptide was evaluated on Polymerization of G-actin to F-actin. A heptapeptide analog of the actin-binding S-site on the myosin head induced polymerization of G-actin to F-actin with a half-maximal concentration of about 110 microM.