InterPro domain: IPR036770

This entry represents the ankyrin repeat-containing domain. These domains contain multiple repeats of a beta(2)-alpha(2) motif. The ankyrin repeat is one of the most common protein-protein interaction motifs in nature. Ankyrin repeats are tandemly repeated modules of about 33 amino acids. They occur in a large number of functionally diverse proteins mainly from eukaryotes. The few known examples from prokaryotes and viruses may be the result of horizontal gene transfers [ 1 ]. The repeat has been found in proteins of diverse function such as transcriptional initiators, cell-cycle regulators, cytoskeletal, ion transporters and signal transducers. The ankyrin fold appears to be defined by its structure rather than its function since there is no specific sequence or structure which is universally recognised by it.

The conserved fold of the ankyrin repeat unit is known from several crystal and solution structures [ 2 , 3 , 4 , 5 ]. Each repeat folds into a helix-loop-helix structure with a beta-hairpin/loop region projecting out from the helices at a 90 ^o angle. The repeats stack together to form an L-shaped structure [ 6 , 6 ].

1. Hundreds of ankyrin-like repeats in functionally diverse proteins: mobile modules that cross phyla horizontally? Proteins 17, 363-74
2. Structure of the p53 tumor suppressor bound to the ankyrin and SH3 domains of 53BP2. Science 274, 1001-5
3. Structure of the cyclin-dependent kinase inhibitor p19Ink4d. Nature 389, 999-1003
4. The structure of GABPalpha/beta: an ETS domain- ankyrin repeat heterodimer bound to DNA. Science 279, 1037-41
5. Structure of an IkappaBalpha/NF-kappaB complex. Cell 95, 749-58
6. Consensus-derived structural determinants of the ankyrin repeat motif. Proc. Natl. Acad. Sci. U.S.A. 99, 16029-34