Using different approaches, two groups have found evidence that myosin is involved in actin assembly. The dynamic nature of actin assembly implied an association with actin-based molecular motors, but the details of this association have remained obscure. In the new work, the two teams determined that type I myosins in yeast associate with WASP-like adapter proteins and components of the Arp2/3 actin nucleation complex, suggesting that myosin I proteins are involved in the assembly of cortical actin filaments.
Evangelista and colleagues (page 353) used two-hybrid and coimmunoprecipitation experiments to identify binding partners for the carboxy-terminal SH3 and acidic domains of Myo3p and Myo5p, functionally redundant type I myosin heavy chain proteins in Saccharomyces cerevisiae. They found that Bee1p (Las17p) and Vrp1p, homologues of the human WASP and WIP adapter proteins, interact with the myosin I SH3 domain. Arc40p...
