Functional characterization of the N-terminal region of myosin-2

J Biol Chem. 2006 Nov 24;281(47):36102-9. doi: 10.1074/jbc.M605171200. Epub 2006 Sep 17.


All class 2 myosins contain an N-terminal extension of approximately 80 residues that includes an Src homology 3 (SH3)-like subdomain. To explore the functional importance of this region, which is also present in most other myosin classes, we generated truncated constructs of Dictyostelium discoideum myosin-2. Truncation at position 80 resulted in the complete loss of myosin-2 function in vivo. Actin affinity was more than 80-fold, and the rate of ADP release approximately 40-fold decreased in this mutant. In contrast, a myosin construct that lacks only the SH3-like subdomain, corresponding to residues 33-79, displayed much smaller functional defects. In complementation experiments with myosin-2 null cells, this construct rescued myosin-2-dependent processes such as cytokinesis, fruiting body formation, and sporogenesis. An 8-fold reduction in motile activity and changes of similar extent in the affinity for ADP and filamentous actin indicate the importance of the SH3-like subdomain for correct communication between the functional regions within the myosin motor domain and suggest that local perturbations in this region can play a role in modulating myosin-2 motor activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / chemistry
  • Adenosine Diphosphate / chemistry
  • Adenosine Triphosphatases / metabolism
  • Amino Acid Sequence
  • Animals
  • Cytokinesis
  • Dictyostelium / metabolism*
  • Genetic Complementation Test
  • Molecular Sequence Data
  • Myosin Type II / chemistry*
  • Myosin Type II / metabolism
  • Myosins / chemistry
  • Protein Structure, Tertiary
  • Sequence Homology, Amino Acid
  • src Homology Domains


  • Actins
  • Adenosine Diphosphate
  • Adenosine Triphosphatases
  • Myosin Type II
  • Myosins