InterPro domain: IPR003311

The Aux/IAA proteins are key regulators of auxin-modulated gene expression [ 1 ]. The plant hormone auxin (indole-3-acetic acid, IAA) regulates diverse cellular and developmental responses in plants, including cell division, expansion, differentiation and patterning of embryo responses [ 2 ]. Auxin can regulate the gene expression of several families, including GH3 and SAUR, as well as Aux/IAA itself. The Aux/IAA proteins act as repressors of auxin-induced gene expression, possibly through modulating the activity of DNA-binding auxin response factors (ARFs). Aux/IAA and ARF are thought to interact through C-terminal protein-protein interaction domains found in both Aux/IAA and ARF.

Recent evidence suggests that Aux/IAA proteins can also mediate light responses [ 3 ]. Some members of the Aux/IAA family are longer and contain an N-terminal DNA binding domain [ 4 ] and may have an early function in the establishment of vascular and body patterns in embryonic and post-embryonic development in some plants.

1. Genetics of Aux/IAA and ARF action in plant growth and development. Plant Mol. Biol. 49, 387-400
2. Recent advances in the study of mechanisms of action of phytohormones. Biochemistry Mosc. 69, 233-47
3. Roles and activities of Aux/IAA proteins in Arabidopsis. Trends Plant Sci. 6, 420-5
4. The Arabidopsis gene MONOPTEROS encodes a transcription factor mediating embryo axis formation and vascular development. EMBO J. 17, 1405-11