Figure 6. CCT chaperonin-assisted early events in TFIID assembly.
a, siRNA-mediated knockdown of CCT subunit TCP1 impedes GFP-TAF5 integration into TFIID. Control cells were treated with a non-targeting siRNA (siNT). Input represent 2% of the protein sample used in each co-IP. Technical replicates n = 2. Uncropped blot/gel images are shown in Supplementary Data Set 1. b, TCP1 knockdown affects nuclear localization of GFP-TAF5; scale bar = 10 μm. Technical replicates n = 2. c, Newly- synthesized TAF5 is captured by the chaperonin (left). The TAF5 N-terminal domain folds autonomously, Folding of the WD40 repeat domain depends on CCT. Release of readily folded TAF5 from the chaperonin requires binding of TAF6-TAF9, resulting in a discrete TAF5-TAF6-TAF9 complex in the cytoplasm. Binding of further TAFs and TBP completes functional holo-TFIID assembly.