HOMOLOGY OF A YEAST ACTIN-BINDING PROTEIN TO SIGNAL TRANSDUCTION PROTEINS AND MYOSIN-I

IN yeast, the cortical actin cytoskeleton seems to specify sites of growth of the cell surface1,2. Because the actin-binding protein ABPlp is associated with the cortical cytoskeleton of Saccharomyces cerevisiae, it might be involved in the spatial organization of cell surface growth3. ABPlp is localized to the cortical cytoskeleton and its overproduction causes assembly of the cortical actin cytoskeleton at inappropriate sites on the cell surface, resulting in delocalized surface growth. We have now cloned and sequen-ced the gene encoding ABPlp. ABPlp is a novel protein with a 50 amino-acid C-terminal domain that is very similar to the SH3 domain in the non-catalytic region of nonreceptor tyrosine kinases (including those encoded by the proto-oncogenes c-src and c-abl), in phopholipase Cγ and in α-spectrin. We also identified an SH3-related motif in the actin-binding tail domain of myosin-I. The identification of SH3 domains in a family of otherwise unrelated proteins that associate with the membrane cytoskeleton indicates that this domain might serve to bring together signal transduction proteins and their targets or regulators, or both, in the membrane cytoskeleton. © 1990 Nature Publishing Group.