The structure of actin filaments and the origin of the axial periodicity in the I -substance of vertebrate striated muscle

Abstract

A discussion of data obtained from electron-photomicrographs as they relate to actin filaments. There is a fundamental difference between the 406 A periodicity in the I-substance and the 435 A repeat of the active sites on the myosin filaments. The latter is a repeat of a helix; the former is probably not.