The Trio family of RhoA guanine nucleotide exchange factors (RhoGEFs) are directly activated by G alpha (q), possibly within a Gq:Trio:RhoA signalling complex, thereby linking Gq to RhoA-mediated processes such as cell migration, proliferation, and contraction. Like most other RhoGEFs, they have a tandem motif consisting of a Dbl homology (DH) and a pleckstrin homology (PH) domain. Trio and Duet have a number of other domains including an immunoglobin domains that may be involved in interacting with Rho, but the considerably smaller GEFT (p63RhoGEF) does not have any identifiable additional domains yet appears to be sufficient to mediate the activation of RhoA by G alpha (q). The structure represented by GEFT is proposed to represent the core of an ancient signal transduction pathway.