Auxin response factors

Auxin response factors (ARFs) are a family of transcription factors that are unique to plants and bind with specificity to auxin response elements (AuxREs) in promoters of primary or early auxin response genes. ARF's have a modular structure with an amino-terminal DNA binding domain, a centralized activation or repression domain, and, in most cases, a carboxy-terminal dimerization domain. The dimerization domain in ARF proteins is related in amino sequence to the dimerization domain in Aux/IAA proteins. Homotypic and heterotypic interactions can occur between ARF and Aux/IAA protein family members. Recent biochemical and genetic studies suggest that the ARF and Aux/IAA proteins play pivotal and concerted roles in regulating the expression of primary/early auxin-responsive genes.