Hsp90aa1 is a molecular chaperone that promotes the maturation, structural maintenance and proper regulation of specific target proteins involved for instance in cell cycle control and signal transduction. Hsp90aa1 undergoes a functional cycle that is linked to its ATPase activity. This cycle probably induces conformational changes in the client proteins, thereby causing their activation. Hsp90aa1 interacts dynamically with various co-chaperones that modulate its substrate recognition, ATPase cycle and chaperone function.