Mediates the uptake of pyruvate into mitochondria. Negatively regulates ABA-induced guard cell signaling and mediates drought stress responses. Abundant in leaf and particularly in the guard cells. By abscisic acid (ABA) and drought stress. Abscisic acid (ABA) hypersensitivity of stomatal movements and enhanced drought tolerance. May be due to an intron retention. Belongs to the mitochondrial pyruvate carrier (MPC) (TC 2.A.105) family.