How to identify the substrates of ATP-binding cassette (ABC) transporters (Plant Physiol)

Plant genomes encode many ATP-binding cassette (ABC) transporters, which mediate the transport of many different substrates involved in development, nutrition and stress responses. Mutants and transgenic plants have been used to understand the in planta roles, yet the identity of substrates transported by many ABC proteins remain unknown. Since these proteins are able to transport many structurally unrelated substrates, and since the identification of substrates is often performed indirectly, substrate identification has been difficult. This review by Lefèvre and Boutry discusses ABC transporters that have unambiguously identified substrates, as well as heterologous and homologous expression systems used to study ABC transporters. They also discuss how current research is elucidating ABC transporter structures, bidirectionality of transport, and the role of post-translational modifications.  (Summary by Julia Miller) Plant Physiol. 10.1104/pp.18.00325