ATP-binding cassette domain of the osmoprotectant proline/glycine betaine uptake system
This family comprises the glycine betaine/L-proline ATP binding subunit in bacteria and its equivalents in archaea. This transport system belong to the larger ATP-Binding Cassette (ABC) transporter superfamily. The characteristic feature of these transporters is the obligatory coupling of ATP hydrolysis to substrate translocation. ABC transporters are a subset of nucleotide hydrolases that contain a signature motif, Q-loop, and H-loop/switch region, in addition to, the Walker A motif/P-loop and Walker B motif commonly found in a number of ATP- and GTP-binding and hydrolyzing proteins.