Probably acts as a GEF (guanine nucleotide exchange factor) for the Rho family of small GTP-binding proteins (G proteins) that stimulates the dissociation of GDP to enable subsequent binding of GTP (By similarity). May also chaperone the processing and/or trafficking of small GTPases independently of GEF activity (By similarity). Involved in the control of polarized cell growth via CDC42-mediated signaling (PubMed:8754839). Involved in the control of cell-wall organization via RHO1-mediated signaling (PubMed:8754839, PubMed:8754840). May also function via RHO2 and RHO4 (PubMed:8754839). Interacts with CDC42; the interaction is direct (PubMed:8754839). Interacts with RHO1; the interaction is direct (PubMed:8754839, PubMed:8754840). Interacts with RHO2 (PubMed:8754839). Interacts with RHO4 (PubMed:8754839). Interacts with CDC11 (PubMed:12665577). Cell polarity defects; delocalized actin patches and abnormal budding (PubMed:8754840). Cell lysis at high temperature (PubMed:8754840). Present with 6330 molecules/cell in log phase SD medium.