PROSITE documentation PDOC51148AXH domain profile
The AXH (ataxin-1 and HMG-box protein 1) domain is a module of ~130 amino acids, which has been identified in ATX1 and in the apparently unrelated transcription factor HBP1 [1]. It is found in many vertebrate and invertebrate proteins. It has been suggested that the AXH domain is a molecular scaffold domain engaged in multiple protein-protein interactions and in RNA binding.
The AXH domain consists of a noncanonical oligonucleotide and oligosaccharide binding (OB) fold. Although sharing a similar OB fold, the structure of the AXH domains from ATX1 (see <PDB:1OA8>) and HBP1 (see <PDB:1V06>) have genuinely distinct folds. The differences are not, as in other chameleon sequences, determined by a different tendency to adopt distinct secondary structures: the two folds share the same secondary structure elements, but these are differently arranged in space. The AXH domain has a chameleon structure in which the N and C termini can adopt distinctly different conformation. Neither of the differences are induced by binding to another molecule. While clearly correlated (sharing a sequence identity of ca. 30% and a homology of ca. 50% depending on the species), AXH has slightly different domain boundaries and distinct properties in ATX1 and HBP1. There is a cluster of charged residues that could constitute a ligand-binding site [2,3].
Some proteins known to contain a AXH domain are listed below:
- Animal ataxin-1 (ATX1), a neurodegenerative disorder protein whose glutamine-repeat expanded form causes spinocerebellar ataxia type 1 (SCA1) in humans and exerts cytotoxicity in Drosophila and mouse.
- Animal Brother of ataxin-1 (Boat) [4].
- Vetebrate HMG box containing protein 1 (HBP1). It is thought to be involved in an architectural regulation of chromatin and in specific gene expression.
The profile we developed covers the entire AXH domain.
Last update:October 2005 / First entry.
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PROSITE method (with tools and information) covered by this documentation:
| 1 | Authors | de Chiara C. Giannini C. Adinolfi S. de Boer J. Guida S. Ramos A. Jodice C. Kioussis D. Pastore A. |
| Title | The AXH module: an independently folded domain common to ataxin-1 and HBP1. | |
| Source | FEBS Lett. 551:107-112(2003). | |
| PubMed ID | 12965213 |
| 2 | Authors | Chen Y.W. Allen M.D. Veprintsev D.B. Loewe J. Bycroft M. |
| Title | The structure of the AXH domain of spinocerebellar ataxin-1. | |
| Source | J. Biol. Chem. 279:3758-3765(2004). | |
| PubMed ID | 14583607 | |
| DOI | 10.1074/jbc.M309817200 |
| 3 | Authors | de Chiara C. Menon R.P. Adinolfi S. de Boer J. Ktistaki E. Kelly G. Calder L. Kioussis D. Pastore A. |
| Title | The AXH domain adopts alternative folds the solution structure of HBP1 AXH. | |
| Source | Structure 13:743-753(2005). | |
| PubMed ID | 15893665 | |
| DOI | 10.1016/j.str.2005.02.016 |
| 4 | Authors | Mizutani A. Wang L. Rajan H. Vig P.J.S. Alaynick W.A. Thaler J.P. |
| Title | Tsai C.-C. Boat, an AXH domain protein, suppresses the cytotoxicity of mutant ataxin-1. | |
| Source | EMBO J. 24:3339-3351(2005). | |
| PubMed ID | 16121196 | |
| DOI | 10.1038/sj.emboj.7600785 |
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