Abstract

This article focuses on ribosome-associated chaperones. A chaperone bound close to the exit tunnel on a ribosome 25 Å from the emerging nascent chain has an effective concentration of 1 x 10 M, which is 4-5 orders of magnitude larger than the concentration of the chaperone in the cytosol. Ribosome-bound chaperones bind nascent chains intramolecularly with rates as large as 10 s in order to keep chains unfolded.

Keywords: Chaperone, holdase, kinetic partitioning, proximity effect, ribosome-associated chaperone