ABC transporters are one of the largest membrane protein families discovered so far (Jumpertz et al., 2009). ABC transporters use the energy of ATP to catalyze the transport of a tremendous variety of substrates across biological membranes in a vectorial fashion. All ABC transporters analyzed so far are composed of two nucleotide-binding domains (NBD) and two transmembrane domains (TMD) that can be arranged in any possible combination. However, additional transmembrane segments or extended NBDs, raise the possibility that these extensions act as platforms to interact with additional proteins with functional or regulatory consequences.

ABC proteins are divided into three major classes corresponding to their overall quaternary structure organization. Class 1 contains ABC transporters whose transmembrane components and ABC domains are fused in a single polypeptide chain. Class 2 is comprised of ABC proteins lacking an integral membrane component or transport function. Class 3 identifies ABC transport systems where the ABC and membrane components are encoded on separate polypeptide chains and where an additional component essential for import processes can be present.

ABC transporters have been ascribed an important role in the development of multi drug resistance.

Jumpertz et al (2009) ABC Transporters: A Smart Example of Molecular Machineries. In: ABC Transporters in Microorganisms. Ponte-Sucre, A (Ed.). Caister Academic Press, Norfolk, UK

Further reading: ABC Transporters in Microorganisms

Labels: ABC transporters, drug resistance, membrane, transport