Auxin efflux transporter that acts as a negative regulator of light signaling to promote hypocotyl elongation. Mediates the accumulation of chlorophyll and anthocyanin, as well as the expression of genes in response to light. Participates in auxin efflux and thus regulates the polar auxin basipetal transport (from auxin-producing leaves to auxin-sensitive tissues, and from root tips to root elongating zone). Involved in diverse auxin-mediated responses including gravitropism, phototropism and lateral root formation. Interacts with 1-naphthylphthalamic acid (NPA), and FKBP42/TWD1. Ubiquitous, mostly in shoot meristems. In seedlings, confined to hypocotyls in darkness, but expressed in all tissues except in hypocotyls in light. In flowers, present in all organs except petals. By auxin (IAA). Induced by red light, but repressed by far-red light. Belongs to the ABC transporter superfamily. ABCB family. Multidrug resistance exporter (TC 3.A.1.201) subfamily.