4.A.7.1.6
The PTS ascorbate transporter subunits IIBC (596 aas and 11 TMSs) and IIA (155 aas).The 3-d structure has been determined at high resolution of the inward open configuration, showing that ascorbate translocation can be achieved by a rigid-body movement of the substrate-binding core domain relative to the V motif domain, which brings along the transmembrane helices TM2 and TM7 of the V motif domain to undergo a winding at the pivotal positions (Luo et al. 2018). This completes the picture of the transport cycle of the ascorbate superfamily of membrane-spanning EIIC components of the PTS.