InterPro domain: IPR001606

The AT-rich interaction domain (ARID) is an ~100-amino acid DNA-binding module found in a large number of eukaryotic transcription factors that regulate cellproliferation, differentiation and development [ 1 , 2 ]. The ARID domain appearsas a single-copy motif and can be found in association with other domains,such as JmjC, JmjN, Tudor and PHD-type zinc finger [ 3 ].

The basic structure of the ARID domain domain appears to be a series of sixalpha-helices separated by beta-strands, loops, or turns, but the structuredregion may extend to an additional helix at either or both ends of the basicsix. Based on primary sequence homology, they can be partitioned into threestructural classes:

• Minimal ARID proteins that consist of a core domain formed by six alpha- helices;
• ARID proteins that supplement the core domain with an N-terminal alpha- helix;
• Extended-ARID proteins, which contain the core domain and additional alpha- helices at their N- and C-termini.

Minimal ARIDs are distributed in all eukaryotes, while extended ARIDs arerestricted to metazoans. The ARID domain binds DNA as a monomer, recognizingthe duplex through insertion of a loop and an alpha-helix into the majorgroove, and by extensive non-specific anchoring contacts to the adjacentsugar-phosphate backbone [ 4 , 4 , 4 ].

Some proteins known to contain a ARID domain are listed below:

• Eukaryotic transcription factors of the jumonji family.
• Mammalian Bright, a B-cell-specific trans-activator of IgH transcription.
• Mammalian PLU-1, a protein that is upregulated in breast cancer cells.
• Mammalian RBP1 and RBP2, retinoblastoma binding factors.
• Mammalian Mrf-1 and Mrf-2, transcriptional modulators of the cytomegalovirus major intermediate-early promoter.
• Drosophila melanogaster Dead ringer protein, a transcriptional regulatory protein required for early embryonic development.
• Yeast SWI1 protein, from the SWI/SNF complex involved in chromatin remodeling and broad aspects of transcription regulation.
• Drosophila melanogaster Osa. It is structurally related to SWI1 and associates with the brahma complex, which is the Drosophila equivalent of the SWI/SNF complex.

1. Solution structure of the DNA binding domain from Dead ringer, a sequence-specific AT-rich interaction domain (ARID). EMBO J. 18, 6084-94
2. The structure of the Dead ringer-DNA complex reveals how AT-rich interaction domains (ARIDs) recognize DNA. EMBO J. 21, 1197-209
3. ARID proteins: a diverse family of DNA binding proteins implicated in the control of cell growth, differentiation, and development. Cell Growth Differ. 13, 95-106
4. Structure and DNA-binding sites of the SWI1 AT-rich interaction domain (ARID) suggest determinants for sequence-specific DNA recognition. J. Biol. Chem. 279, 16670-6