Sti1/Hop Plays a Pivotal Role in Hsp90 Regulation Beyond Bridging Hsp70
Since its initial characterization, Hop (Hsp90/Hsp70 organizing protein), known as Sti1 in yeast (stress inducible) is mostly understood to serve as a bridge that facilitates transfer of substrate “client” proteins from Hsp70 to Hsp90. Recent work has shown that Sti1 regulates Hsp90 in a manner distinct from its role as a bridge to Hsp70. This second function of Sti1 seems to be to position Hsp90 for subsequent steps of the client maturation cycle, after the client has been transferred from Hsp70. Thus, Sti1/Hop occupies a central gatekeeper role in the Hsp90 reaction cycle, by first facilitating client access to Hsp90 and then promoting the next steps of the cycle.
KeywordsChaperone Co-chaperone Hop Hsp Hsp70 Hsp90 Sti1
Hsp90/Hsp70 organizing protein
Heat shock protein
Sti1-dependent carboxy-terminal proximal
Sti1-dependent amino-terminal proximal
We thank our National Institutes of Health colleagues for insightful discussions and help with the manuscript. This work was supported by the Intramural Program of the National Institutes of Health, National Institute of Diabetes and Digestive and Kidney diseases.
- Millson SH, Truman AW, King V, Prodromou C, Pearl LH, Piper PW (2005) A two-hybrid screen of the yeast proteome for Hsp90 interactors uncovers a novel Hsp90 chaperone requirement in the activity of a stress-activated mitogen-activated protein kinase, Slt2p (Mpk1p). Eukaryot Cell 4:849–860CrossRefGoogle Scholar