ArF2

Auxin response factor 2 (ARF2) is a transcription factor in plants that belongs to the Auxin Response Factor family. In Arabidopsis thaliana, ARF2 binds to auxin response elements in the promoters of auxin-regulated genes and modulates their transcription in response to auxin levels. ARF proteins have three conserved features: an N-terminal B3-type DNA-binding domain, a middle region whose composition determines whether the protein acts as a transcriptional activator or repressor, and a C-terminal dimerization domain that mediates interactions with Aux/IAA co-repressors and other ARFs. The activity of ARF2 is regulated by the auxin signaling pathway through Aux/IAA co-repressors; in low auxin, Aux/IAAs bind ARF2 and recruit corepressors to inhibit transcription. When auxin is abundant, Aux/IAA proteins are degraded, freeing ARF2 to regulate target genes. ARF2 can form homo- or heterodimers, enabling combinatorial control of gene expression, and it localizes to the nucleus.

ARF2 participates in multiple developmental processes, including leaf growth and senescence, seed and fruit development, and root architecture, with genetic studies showing that altering ARF2 activity can affect organ size, senescence timing, and other growth traits. Across plant species, ARF2 homologs contribute to auxin-responsive transcriptional programs and interact with other components of the auxin signaling network. Ongoing research aims to clarify context-specific roles and regulatory circuits involving ARF2.