Format

Send to

Choose Destination
Biophys J. 2005 May;88(5):L30-2. Epub 2005 Mar 11.

Differential labeling of myosin V heads with quantum dots allows direct visualization of hand-over-hand processivity.

Author information

1
Department of Molecular Physiology & Biophysics, University of Vermont, Burlington, Vermont 05405, USA. warshaw@physiology.med.uvm.edu

Abstract

The double-headed myosin V molecular motor carries intracellular cargo processively along actin tracks in a hand-over-hand manner. To test this hypothesis at the molecular level, we observed single myosin V molecules that were differentially labeled with quantum dots having different emission spectra so that the position of each head could be identified with approximately 6-nm resolution in a total internal reflectance microscope. With this approach, the individual heads of a single myosin V molecule were observed taking 72-nm steps as they alternated positions on the actin filament during processive movement. In addition, the heads were separated by 36 nm during pauses in motion, suggesting attachment to actin along its helical repeat. The 36-nm interhead spacing, the 72-nm step size, and the observation that heads alternate between leading and trailing positions on actin are obvious predictions of the hand-over-hand model, thus confirming myosin V's mode of walking along an actin filament.

PMID:
15764654
PMCID:
PMC1305523
DOI:
10.1529/biophysj.105.061903
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center