Defining protein interactions with yeast actin in vivo

Using the two-hybrid protein interaction reporter system, actin, profilin, Srv2p and two SH3-containing proteins are found to bind yeast actin in vivo. When tested for ability to interact with 35 actin mutations distributed over the monomer surface, distinct subsets of mutations characteristic for each putative ligand are found to disrupt binding. In particular, the pattern of differential interactions for the actin-actin interaction is consistent with published structures for the actin filament. Despite functional similarities, the patterns of differential interaction for Srv2p and profilin are different. In contrast, the patterns for profilin and the SH3 domain proteins suggest a shared binding site and commonality in mechanism.