Expression of the mnh2 operon in E.coli is not able to catalyze Na(+)Li(+)/H(+) antiport. It does however confer higher growth rates than the control strain at up to pH 9.5. The operon may encode an NADH-ubiquinone oxidoreductase. May form a heterooligomeric complex that consists of seven subunits: mnhA2, mnhB2, mnhC2, mnhD2, mnhE2, mnhF2 and mnhG2. Belongs to the CPA3 antiporters (TC 2.A.63) subunit D family.