Guanine nucleotide exchange factor that promotes the exchange of GSP1/GSP2-bound GDP by GTP and controls RNA metabolism and transport. Involved in yeast pheromone response pathway and in mRNA metabolism. Involved in nuclear pore complex (NPC) assembly and required for mRNA and ribosome nuclear export. Binds chromatin and is involved NPC-mediated transcriptional control. Component of a multicomponent complex composed of six to seven proteins, which has a collective molecular mass greater than 150 kDa. Interacts with GSP1 and YRB2. By pheromone. Phosphorylated; possibly by KSP1. Present with 12100 molecules/cell in log phase SD medium.