HSP90b Protein, Human (sf9)

Hsp90 is a molecular chaperone that facilitates the maturation, structural maintenance, and proper regulation of specific target proteins involved in processes such as cell cycle control and signal transduction. Its functional cycle is linked to ATPase activity, inducing conformational changes in client proteins to activate them. Hsp90 dynamically interacts with various co-chaperones, which modulate substrate recognition, ATPase cycling, and chaperone function. It engages with diverse client protein classes through co-chaperone adapters, forming functional chaperone complexes. After completing the chaperoning process, properly folded clients and co-chaperones dissociate, leaving Hsp90 in an ADP-bound partially open state before ADP release resets the cycle. Beyond chaperoning, Hsp90 regulates transcription by modulating transcription factor levels, epigenetic modifiers (e.g., histone deacetylases or DNA methyltransferases), and histone eviction from gene promoters. It antagonizes STUB1-mediated inhibition of TGF-beta signaling, promotes cell differentiation, and supports STAT1 phosphorylation/activation. Hsp90 also mediates ERGIC translocation of leaderless cargos (e.g., IL-1) via the cargo receptor TMED10. During microbial infection, it binds N. meningitidis NadA, potentially interfering with host cell invasion.