Part of the tripartite efflux system MacAB-TdeA. MacB is a non-canonical ABC transporter that contains transmembrane domains (TMD), which form a pore in the inner membrane, and an ATP-binding domain (NBD), which is responsible for energy generation. Confers resistance against macrolides. Homodimer. Part of the tripartite efflux system MacAB-TdeA, which is composed of an inner membrane transporter, MacB, a periplasmic membrane fusion protein, MacA, and an outer membrane component, TdeA. The complex forms a large protein conduit and can translocate molecules across both the inner and outer membranes. Interacts with MacA. Mutation does not produce a noticeable phenotype or alter the drug resistance profile and the hemolytic activity of A.actinomycetemcomitans. Belongs to the ABC transporter superfamily. Macrolide exporter (TC 3.A.1.122) family. Extended N-terminus.