ABC-Transporters

Synonyms

Multidrug resistance transporters; Traffic ATPases; Permeases (for import systems)

Definition

ABC (ATP-binding cassette)-transporters are membrane-embedded proteins with a characteristic ABC domain that utilize the energy from ATP hydrolysis for the transport of their substrates across a cellular membrane.

Characteristics

The superfamily of ABC-transporters comprises one of the most abundant protein families in nature. These transporters are believed to date back in evolutionary time more than 3 billion years and are distributed in all three kingdoms of living organisms, archaea, eubacteria, and eukaryotes. ABC-transporters have to be distinguished from ABC-proteins. Both types of proteins are defined by the presence of a highly conserved ~215 amino acids consensus sequence designated as ABC domain or nucleotide-binding domain (NBD). The domain contains two short peptide motifs, a glycine-rich Walker A and a hydrophobic Walker B motif, both involved in ATP binding and...