Together with GPA1, may regulate the cell cycle via a signaling cascade that uses phosphatidylinositol-specific phospholipase C (PI-PLC) as an effector and inositol 1,4,5-trisphosphate(IP(3)) as a second messenger. Promotes PI-PLC activity and IP(3) accumulation. Involved in the blue light (BL) signaling. Together with GPA1 and ADT3, required for BL-mediated synthesis of phenylpyruvate and subsequently of phenylalanine (Phe), in etiolated seedlings. Probably involved in cytokinin signal transduction. Plays a positive role in gibberellin- (GA) and brassinosteroid- (BR) regulated seed germination, probably independently of a heterotrimeric G-protein. Mediates seed dormancy abolition, and promotes seed germination and flowering. Interacts with GPA1. Localized to the outer edge of the leaf epidermal cells in a punctuate pattern. Mostly present in the meristematic regions. Expressed at low levels in seedlings, vascular tissues of cotyledons, hypocotyl, and roots, stems, leaves, flowering buds and siliques. In dark-grown seedlings, localized in the cotyledons and the hook. In seedlings, mostly expressed in small roots, and to a lower extent in hypocotyls. In young plants, equaly expressed in leaves, roots, and shoot tip. In old plants, present in roots, flower buds and young siliques, but not in leaves. Modulated during the cell cycle with a peak during the early G(1) phase. Improved drought tolerance accompanied by lower rates of water loss. Impaired sensitivity to gibberellin (GA) and brassinosteroid (BR) in seed germination. Hypersensitivity to ABA and glucose (Glc) during and after seed germination. Altered response to blue light (BL). Belongs to the G-protein coupled receptor 2 family. An article reported a role as negative regulator of ABA during seed germination; however, this paper was later retracted.