Attachment of Anti-GFP Antibodies to Microspheres for Optical Trapping Experiments

James A. Spudich, Sarah E. Rice, Ronald S. Rock, Thomas J. Purcell and Hans M. Warrick

In vitro motility assays enabled the analysis of coupling between ATP hydrolysis and movement of myosin along actin filaments or kinesin along microtubules. Single-molecule assays using laser trapping have been used to obtain more detailed information about kinesins, myosins, and processive DNA enzymes. The combination of in vitro motility assays with laser-trap measurements has revealed detailed dynamic structural changes associated with the ATPase cycle. This protocol describes a method for attaching anti-GFP (green fluorescent protein) antibodies to microspheres. GFP-motor fusion proteins can then be adsorbed to the microspheres for use in single-molecule motility studies and optical trapping experiments.

DOI

The Optical Trapping Dumbbell Assay for Nonprocessive Motors or Motors That Turn around Filaments

James A. Spudich, Sarah E. Rice, Ronald S. Rock, Thomas J. Purcell and Hans M. Warrick

In vitro motility assays enabled the analysis of coupling between ATP hydrolysis and movement of myosin along actin filaments or kinesin along microtubules. Single-molecule assays using laser trapping have been used to obtain more detailed information about kinesins, myosins, and processive DNA enzymes. The combination of in vitro motility assays with laser-trap measurements has revealed detailed dynamic structural changes associated with the ATPase cycle. This protocol describes the preparation of biotin–actin filaments and coverslips coated with polystyrene beads. These are then used in optical trapping dumbbell assays to study interactions between motors and filaments.

DOI

Optical Traps to Study Properties of Molecular Motors

James A. Spudich, Sarah E. Rice, Ronald S. Rock, Thomas J. Purcell and Hans M. Warrick

In vitro motility assays enabled the analysis of coupling between ATP hydrolysis and movement of myosin along actin filaments or kinesin along microtubules. Single-molecule assays using laser trapping have been used to obtain more detailed information about kinesins, myosins, and processive DNA enzymes. The combination of in vitro motility assays with laser-trap measurements has revealed detailed dynamic structural changes associated with the ATPase cycle. This article describes the use of optical traps to study processive and nonprocessive molecular motor proteins, focusing on the design of the instrument and the assays to characterize motility.

DOI