A mechanical function of myosin II in cell motility

Patrick Y. Jay, Peter A. Pham, Scott A. Wong, Elliot L. Elson

Research output: Contribution to journalArticlepeer-review

80 Scopus citations


Myosin II mutant Dictyostelium amoebae crawl more slowly than wild-type cells. Thus, myosin II must contribute to amoeboid locomotion. We propose that contractile forces generated by myosin II help the cell's rear edge to detach from the substratum and retract, allowing the cell to continue forward. To test this hypothesis, we measured the speed of wild-type and myosin II null mutant Dictyostelium cells on surfaces of varying adhesivity. As substratum adhesivity increased, the speed of myosin II null mutant cells decreased substantially compared to wild-type cells, suggesting that the mutant is less able to retract from sticky surfaces. Furthermore, interference reflection microscopy revealed a myosin-II-dependent contraction in wild-type but not null mutant cells that is consistent with a balance of adhesive and contractile forces in retraction. Although myosin II null mutant cells have a defect in retraction, pseudopod extension does not cause the cells to become elongated on sticky surfaces. This suggests a mechanism, based possibly on cytoskeletal tension, for regulating cell shape in locomotion. The tension would result from the transmission of tractional forces through the cytoskeletal network, providing the myosin II null mutant with a limited means of retraction and cell division on a surface.

Original languageEnglish
Pages (from-to)387-393
Number of pages7
JournalJournal of cell science
Issue number1
StatePublished - Jan 1 1995


  • Adhesion
  • Cell motility
  • Cytoskeleton
  • Dictyostelium
  • Myosin II


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