Fig. 5. The binding between scallop striated adductor myosin and chicken fast skeletal F-actin and the influence of the twitchin D2 peptide under catch conditions. SDS-PAGE results for the mixtures indicated are shown. S, supernatant; P, pellet (see Materials and methods). (A) Results using a molar ratio of peptide:myosin of 50:9. TWD2-S facilitated the binding between actin and myosin, whereas the thiophosphorylated form (thio-TWD2-S) did not. Arrowheads indicate F-actin, which co-sedimented with myosin. (B) The concentration-dependence of F-actin binding with myosin via TWD2-S. Samples for SDS-PAGE contained 10 µg actin (S) or myosin (P). For the actin–myosin coprecipitate, samples applied contained 10 µg myosin.