 Auxin response factor

An auxin response factor is a plant transcription factor that binds auxin response elements and helps regulate gene expression. The factor is a protein, whereas the response element is DNA. Its name concerns the regulatory pathway; it does not make the protein simply another name for an auxin receptor.

The 1997 characterization of auxin response factor 1 connected a DNA-binding region with sequence-specific recognition and identified a separate region associated with protein interactions. This provides an illuminating division of functions: recognizing a regulatory sequence and interacting with another regulator need not be the same molecular task.^[ref]

The companion reporter experiments showed interactions with Aux/IAA proteins and repression of auxin-responsive reporter genes. A hypothetical comparison holding hormone concentration fixed could therefore still yield different reporter outputs when regulatory-protein activity differs. Binding, regulatory interactions and transcriptional output must be distinguished; identifying one factor does not prove that every member of its family activates every target in the same way.^[ref]