Involved in photorespiratory metabolism. Acts probably as a carrier for a glycine decarboxylase (GDC) cofactor or, alternatively, may act as a mitochondrial glycine shuttle. Involved in the transition from the embryonic stage to the juvenile autotrophic stage. High expression in cotyledons, leaves, flowers and developing siliques. Lower expression in roots and maturing siliques. Not detected in meristematic tissues. Detected two days after germination and reached a maximum at three days of growth. Up-regulated by light and down-regulated by norflurazon and lincomycin. Low expression in the dark. Chlorotic leaves and impaired growth when grown under ambient air, but normal growth under CO(2)-enriched air. Belongs to the mitochondrial carrier (TC 2.A.29) family.