ABC transporter is first discovered in bacteria. It is a transport ATPase (transport ATPase) on the bacterial plasma membrane and belongs to a large and diverse protein family. The ABC transporter contains at least two conserved regions: a highly conserved ATP binding cassette (ABC) and a less conserved transmembrane domain (TMD). In some bacterial transport proteins, these regions are on different polypeptides. Most ABC transporters act as dimers and consist of four domains: two ABC modules and two TMDs. ABC transporters usually comprise multiple subunits, one or two of which are transmembrane proteins, and one or two are membrane-associated AAA ATPase. The function of the intact inner membrane protein is to transport the substrate across the membrane and to recognize the substrate . The ATPase subunit binds the adenosine triphosphate (ATP) and hydrolysis ATP to provide the energy required for substrate transport across the membrane to absorb or export the substrate.