Characterization of the interaction of Aha1 with components of the Hsp90 chaperone machine and client proteins

Liang Sun, Thomas Prince, Jacob R. Manjarrez, Bradley T. Scroggins, Robert L. Matts

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31 Scopus citations


The activator of Hsp90 ATPase, Aha1, is an Hsp90 co-chaperone that has been suggested to act as a general stimulator of Hsp90 function. In this report, we have characterized the interaction of Aha1 with Hsp90 and its co-chaperones in rabbit reticulocyte lysate (RRL) and in HeLa cell extracts. Complexes formed by Aha1 with Hsp90 in RRL were stabilized by molybdate and contained the co-chaperones FKBP52 and p23/Sba1, but lacked HOP/Sti1 and Cdc37. Aha1 complexes isolated from HeLa cell extracts also contained Hsp70 and DNAJA1. Over-expression of Aha1 has been reported to stimulate the activity of v-Src and steroid hormone receptors ectopically expressed in yeast, however, no interaction between Aha1 and nascent v-Src or the progesterone receptor could be detected in RRL. Contrary to expectations, over-expression of Aha1 also inhibited the rate of Hsp90-dependent refolding of denatured luciferase. A number of potential client proteins that specifically associated with Aha1 were identified by liquid chromatography/ tandem mass spectrometry (LC-MS/MS) and verified by Western blotting. The proteins identified suggest that Aha1 may play roles in modulating RNA splicing and DNA repair, in addition to other cellular processes.

Original languageEnglish
Pages (from-to)1092-1101
Number of pages10
JournalBiochimica et Biophysica Acta - Molecular Cell Research
Issue number6
StatePublished - Jun 2012
Externally publishedYes


  • Activator of Hsp90 ATPase
  • Aha1-interacting protein
  • Heat shock protein 90
  • Hsp90 inhibitor
  • Non-receptor tyrosine kinase v-Src
  • Progesterone receptor


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