2.A.66.1.61
Vacuolar nicotine exporter (from the cytoplasm into the vacuole), the NtMATE2 transporter, also designated the DETOXIFICATION 40-like protein, of 500 aas and 12 TMSs in a 6 + 6 TMS arrangement. NtMATE2 is located in the vacuole membrane of the tobacco plant root and is involved in the transport of nicotine, a secondary or specialized metabolic compound in Solanaceae ((Shoji et al. 2009). The crystal structures of NtMATE2 in its outward-facing forms have been determined (Tanaka et al. 2021). The overall structure has a bilobate V-shape with pseudo-symmetrical assembly of the N- and C-lobes. In one crystal structure, the C-lobe cavity of NtMATE2 interacts with an unidentified molecule that may mimic a substrate. NtMATE2-specific conformational transitions imply that an unprecedented movement of the transmembrane alpha-helix 7 (TMS7) is related to the release of the substrate into the vacuolar lumen (Tanaka et al. 2021).