2.A.3.7.3
Glutamate:GABA antiporter, GadC (YcaM). GadC, transports GABA/Glu only under acidic conditions, with no detectable activity at pH  values higher than 6.5 (Ma et al., 2012). Ma et al. (2012) determined the crystal structure of GadC at 3.1 Å resolution under basic conditions. GadC, comprising 12 TMSs, exists in a closed state, with its carboxy-terminal domain serving as a plug to block an otherwise inward-open conformation. Structural and biochemical analyses revealed the essential transport residues, identified the transport path and suggested a transport mechanism involving the rigid-body rotation of a helical bundle for GadC and other amino acid antiporters.  Both this glutamate- and the arginine (AdiC; TC#2.A.3.2.5)-dependent acid resistance systems increase the internal pH and reverse the transmembrane potential (Richard and Foster 2004).