InterPro domain: IPR013538

This family includes eukaryotic, prokaryotic and archaeal proteins that bear similarity to a C-terminal region of human activator of 90kDa heat shock protein ATPase homologue 1 (AHSA1/p38, O95433 ). This protein is known to interact with the middle domain of Hsp90, and stimulate its ATPase activity [ 1 ]. It is probably a general up regulator of Hsp90 function, particularly contributing to its efficiency in conditions of increased stress [ 2 ]. p38 is also known to interact with the cytoplasmic domain of the VSV G protein, and may thus be involved in protein transport [ 3 ]. It has also been reported as being under expressed in Down's syndrome. This region is found repeated in two members of this family ( Q8XY04 and Q6MH87 ).

1. Aha1 binds to the middle domain of Hsp90, contributes to client protein activation, and stimulates the ATPase activity of the molecular chaperone. J. Biol. Chem. 278, 17228-35
2. Activation of the ATPase activity of hsp90 by the stress-regulated cochaperone aha1. Mol. Cell 10, 1307-18
3. p38: A novel protein that associates with the vesicular stomatitis virus glycoprotein. Biochem. Biophys. Res. Commun. 287, 574-82