Skip to main content
. Author manuscript; available in PMC: 2016 Aug 19.
Published in final edited form as: Cell. 2016 Jun 2;165(6):1440–1453. doi: 10.1016/j.cell.2016.05.037

Figure 7. Specialized APC/C–E2 Architectures for Multiubiquitination and UB Chain Elongation.

Figure 7

(A) Processive multiubiquitination occurs by APC/C's APC2 cullin (green)-APC11 RING (blue) positioning UBE2C proximal to substrate (red), reducing the search volume for catalytic encounter while substrate-linked UB (yellow) binds the RING exosite to increase the evolving ubiquitinated substrate's lifetime on APC/C and enhance processivity. Each UB transfer cycle is accompanied by catalytic core dynamics releasing the used UBE2C for replacement by a charged UBE2C~UB to donate the next UB for ligation.

(B) Specialized architecture for UB chain elongation. APC2/APC4 recruits UBE2S's CTP, APC2 (cullin) places UBE2S's catalytic UBC domain, and APC11's RING guides the acceptor UB's Lys11 to the active site. Location of UBE2S at the edge of APC/C would accommodate growth of long UB chains.