Members of this family, which are predominantly found in the protein 'Activator of Hsp90 ATPase' adopt a secondary structure consisting of an N-terminal alpha-helix leading into a four-stranded meandering antiparallel beta-sheet, followed by a C-terminal alpha-helix. The two helices are packed together, with the beta-sheet curving around them. They bind to the molecular chaperone HSP82 and stimulate its ATPase activity [1].

1: Structural basis for recruitment of the ATPase activator Aha1 to the Hsp90 chaperone machinery. Meyer P, Prodromou C, Liao C, Hu B, Roe SM, Vaughan CK, Vlasic I, Panaretou B, Piper PW, Pearl LH; EMBO J. 2004;23:1402-1410. PMID:15039704