Myosin lever-arm length. Examination of the rates of actin movement supported by a set of myosin mutants with different numbers of light-chain binding sites revealed a linear relation; the greater the number of light-chain binding sites (and, hence, the longer the lever arm), the faster the sliding velocity.

[Data from T. Q. P. Uyeda, P. D. Abramson, and J. A. Spudich, Proc. Natl. Acad. Sci. U. S. A. 93:4459–4464, 1996.]