Association of actin and myosin with secretory granule membranes.

Abstract

ACTIN and myosin have been found in many non-muscle cells1. They are presumed to function in the generation of the force required in the various expressions of cytoplasmic or cell motility. Although both have been found in association with the plasma membrane2–5, nothing is known about the nature or consequences of this association. Equally uncertain is the mechanism of movement of secretory granules : synaptic vesicles, for example, are transported along neurones at high rates (up to 20 cm d−1)6, probably in association with microtubules7. Roles for actomyosin in this process8 and in exocytosis9 have been proposed. We have used a new approach to the problem of actomyosin-membrane interaction, and report here the binding of actin and myosin in vitro to a purified cytoplasmic membrane component.