Ordered ATP hydrolysis in the Hsp90 chaperone is regulated by Aha1 and a conserved post-translational modification.

Hsp90 is a dimeric molecular chaperone that is important for the folding, stabilization, activation, and maturation of hundreds of protein substrates called "clients" in cells. Dozens of co-chaperones and hundreds of post-translational modifications (PTMs) regulate the ATP-dependent client activation cycle. The Aha1 co-chaperone is the most potent stimulator of the ATPase cycle of Hsp90 and phosphorylation of threonine 22 in Hsp90 can regulate the recruitment of Aha1 in cells.

Recruitment of Ahsa1 to Hsp90 is regulated by a conserved peptide that inhibits ATPase stimulation.

Hsp90 is a molecular chaperone that acts on its clients through an ATP-dependent and conformationally dynamic functional cycle. The cochaperone Accelerator of Hsp90 ATPase, or Ahsa1, is the most potent stimulator of Hsp90 ATPase activity. Ahsa1 stimulates the rate of Hsp90 ATPase activity through a conserved motif, NxNNWHW.

Granulin Increases Resistance to Infection in Several Species and Induces the Production of Reactive Oxygen Species by Haemocytes.

Gastropod molluscs, which have co-evolved with parasitic digenean trematodes for millions of years, utilize circulating heamocytes as the primary method of containing and killing these invading parasites. In order to do so, they must generate suitable amounts of haemocytes that are properly armed to kill parasitic worms. One method by which they generate the haemocytes required to initiate the appropriate cell mediated immune response is via the production and post-translational processing of granulins.