A PERSONAL VIEW OF MUSCLE AND MOTILITY MECHANISMS

This is a personal account of some of the successive steps in our unde rstanding of the structural mechanism of muscle contraction during the last 45 years. It describes how I, as an ex-physicist, came to be stu dying muscle by X-ray diffraction in 1949; how the concepts of the dou ble array of actin and myosin filaments and, later, the overlapping fi lament model and the sliding filament mechanism were developed; and ho w further electron microscope findings of the structural polarity of m uscle filaments led to the suggestion that analogous structures and me chanisms might be involved in cellular motility. The article describes briefly how synchrotron radiation has made it possible to obtain deta iled structural information about contracting muscle with millisecond time resolution and discusses some of the recent major advances in the field and the prospects of reaching a full understanding of the contr action mechanism.