Chapter 3 Motility of Myosin I on Planar Lipid Surfaces

Abstract

Publisher Summary This chapter examines method for producing motility on planar lipid membranes. The methods are described in specific terms, calling for myosin I, actin, and certain buffers. Variations on the method may become evident for other applications, including other myosins and microtubule motor proteins. Two evolving technologies—namely, the reconstitution of in vitro motility and the formation of substrate-supported planar membranes are combined, to reconstitute the movement of actin filaments relative to lipid membranes with purified myosin. This provides a functional test for two of the properties of myosin I: binding to phospholipids attributed to domains in the tail and movement of actin filaments attributed to the head of the myosin I molecule. These separate domains of myosin I potentially enable membrane-mediated movement. The supported planar membranes are good models for biological membranes. The phospholipids in supported planar membranes share many important physical properties with the phospholipids in biological membranes, including a lateral diffusion constant of ∼ 10-8 cm2 s-1, a packing density of ∼70 A2 per molecule, and the coexistence of liquid and crystal domains.