SH3 domain-containing scaffold protein; regulates the guanine exchange factor (GEF) activity of Cdc24p and Cla4p-mediated phosphorylation of Cdc24p, contributing to the regulation of Cdc42p, polarity axis establishment and morphogenesis; scaffold protein that utilizes multivalent lipid binding sites to target and concentrate complexes of polarity establishment proteins at sites of polarized growth during growth and mating; regulates homotypic vacuole fusion