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An intact SH3 domain is required for myosin I‐induced actin polymerization
Author(s) -
Geli M. Isabel,
Lombardi Ruben,
Schmelzl Birgit,
Riezman Howard
Publication year - 2000
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/19.16.4281
Subject(s) - biology , actin , myosin , actin binding protein , microbiology and biotechnology , actin remodeling , actin cytoskeleton , wiskott–aldrich syndrome protein , sh3 domain , cytoskeleton , mdia1 , plasma protein binding , formins , saccharomyces cerevisiae , atp hydrolysis , yeast , biochemistry , proto oncogene tyrosine protein kinase src , phosphorylation , cell , atpase , enzyme
The yeast type I myosins ( MYO3 and MYO5 ) are involved in endocytosis and in the polarization of the actin cytoskeleton. The tail of these proteins contains a Tail Homology 2 (TH2) domain that constitutes a putative actin‐binding site. Because of the important mechanistic implications of a second ATP‐independent actin‐binding site, we analyzed its functional relevance in vivo . Even though the myosin tail interacts with actin, and this interaction seems functionally important, deletion of a major portion of the TH2 domain did not abolish interaction. In contrast, we found that the SH3 domain of Myo5p significantly contributes to this interaction, implicating other proteins. We found that Vrp1p, the yeast homolog of WIP [Wiskott–Aldrich syndrome protein (WASP)‐interacting protein], seems necessary to sustain the Myo5p tail–F‐actin interaction. Consistent with recent results implicating the yeast type I myosins in regulating actin polymerization in vivo , we demonstrate that the C‐terminal domain of Myo5p is able to induce cytosol‐dependent actin polymerization in vitro , and that this activity requires both an intact Myo5p SH3 domain and Vrp1p.