G protein gamma subunit; forms dimer with Ste4p to activate mating signaling pathway, heterotrimer with Gpa1p, Ste4p to dampen signaling; C-terminus is palmitoylated and farnesylated, which are required for normal signaling; N-terminal phosphorylation of Ste18p functions synergistically with Fus3p docking site on Ste5p to restrict Ste5p plasma membrane recruitment and signaling; combinatorial phosphorylation at S3 and S7, by pheromone and pH stress, modulates Ste18p structure, Fus3p activation