| The interaction of one of these clones , Activator of Heat Shock 90 kDa Protein ( Aha 1 ) , with GCH 1 was validated by glutathione s transferase ( GST ) pull down assay . ^^^ Although the physiological relevance of the Aha 1 GCH1 interaction requires further study , Aha 1 may recruit GCH 1 into the endothelial nitric oxide synthase / heat shock protein ( eNOS / Hsp90 ) complex to support changes in endothelial nitric oxide production through the local synthesis of BH4 . . ^^^ |