Mechanism of Action of ABC Importers: Conservation, Divergence, and Physiological Adaptations

- ABC transporters have diverse physiological roles.
- Different 3D folds of the transmembrane domain have been conserved.
- Each fold is associated with a different mechanism of action.
- The different mechanisms are tuned to the physiological role of the system.

The past decade has seen a remarkable surge in structural characterization of ATP binding cassette (ABC) transporters, which have spurred a more focused functional analysis of these elaborate molecular machines. As a result, it has become increasingly apparent that there is a substantial degree of mechanistic variation between ABC transporters that function as importers, which correlates with their physiological roles. Here, we summarize recent advances in ABC importers' structure-function studies and provide an explanation as to the origin of the different mechanisms of action.

Graphical Abstract286