3.A.2.1.12
F-type ATPase lacking a δ-subunit, but having another subunit, AtpR of 104 aas and 3 TMSs that may replace the δ-subunit.  Has a c-subunit that shows the expected residues that comprise a Na⁺ binding site, so it may be a Na⁺ exporting ATPase.  It is in a family of similar ATPases that all lack δ-subunits and have been called N-ATPases (Na⁺-transporting) (Dibrova et al. 2010). They appear to be subject to horizontal transfer and represent a second type of F-type ATPase, the other transporting protons. They are found in a variety of bacteria and archaea (Dibrova et al. 2010). The AtpQ protein may be a Mg²⁺ channel.