G. Cuda et al., IN-VITRO ACTIN FILAMENT SLIDING VELOCITIES PRODUCED BY MIXTURES OF DIFFERENT TYPES OF MYOSIN, Biophysical journal, 72(4), 1997, pp. 1767-1779
Using in vitro motility assays, we examined the sliding velocity of ac
tin filaments generated by pairwise mixings of six different types of
actively cycling myosins. In isolation, the six myosins translocated a
ctin filaments at differing velocities. We found that only small propo
rtions of a more slowly translating myosin type could significantly in
hibit the sliding velocity generated by a myosin type that translocate
d filaments rapidly. In other experiments, the addition of noncycling,
unphosphorylated smooth and nonmuscle myosin to actively translating
myosin also inhibited the rapid sliding velocity, but to a significant
ly reduced extent. The data were analyzed in terms of a model derived
from the original working cross-bridge model of A. F. Huxley. We found
that the inhibition of rapidly translating myosins by slowly cycling
was primarily dependent upon only a single parameter, the cross-bridge
detachment rate at the end of the working powerstroke. In contrast, t
he inhibition induced by the presence of noncycling, unphosphorylated
myosins required a change in another parameter, the transition rate fr
om the weakly attached actomyosin state to the strongly attached state
at the beginning of the cross-bridge power stroke.