Abscisic acid receptor. The GDP-bound form exhibits greater abscisic acid binding than the GTP-bound form (PubMed:19135895). Required for seedling growth and fertility (PubMed:23001037). The GTPase activity is Mg(2+) dependent and is strongly inhibited by the interaction with GPA1. Interacts with GPA1. Expressed in cotyledons, leaves, stems, roots, flowers and guard cells. Not induced by abscisic acid, cold, salt or drought treatments. No visible phenotype; due to the redundancy with GTG1. The double mutants gtg1 and gtg2 are hyposensitive to abscisic acid. Has both a topology similar to GPCRs and a GTP-binding/GTPase activity. Belongs to the Golgi pH regulator (TC 1.A.38) family.