Part of an energy-coupled inorganic carbon pump; its substrate may be carbon dioxide. Expression of both dabA2 and dabB2 (DAB2) restores growth in ambient air to E.coli deleted of its carbonic anhydrase genes (called CAfree, deletion of 'can' and 'cynT'); neither dabA2 or dabB2 alone is sufficient. Rescue is pH-independent, suggesting it transports CO(2) and not carbonate ions. Together the genes allow greater than normal uptake of inorganic carbon by E.coli (PubMed:31406332). Uptake of carbon dioxide rather than bicarbonate has been suggested based on kinetic calculations (Probable). Uptake of inorganic carbon by cells in the presence of thiosulphate is fully inhibited by the uncouplers carbonyl cyanide m-chlorophenyl hydrazone (CCCP), carbonyl cyanide p-trifluoromethoxyphenyl hydrazone (FCCP), S13 or SF6847. Not inhibited by the ATPase inhibitor N,N-dicyclohexylcarbodiimide (DCCD) (Ref.2). Inorganic carbon uptake is inhibited by the ionophore carbonyl cyanide m-chlorophenyl hydrazone (CCCP), suggesting uptake is coupled to a cation gradient (PubMed:31406332). Forms a complex with DabA2, possibly a heterodimer. Required for growth in ambient air. Belongs to the inorganic carbon transporter (TC 9.A.2) DabB family.