What is the function of p31 comet in checkpoint silencing?
The spindle assembly checkpoint generates the Mitotic Checkpoint Complex containing closed Mad2, BubR1, Bub3 and Cdc20, which potently inhibits APC/C until all kinetochores attach. Checkpoint silencing requires active disassembly of this inhibitor once alignment completes. p31comet, also called MAD2L1BP and Trip13 adaptor, functions as dedicated MCC antagonist. Structurally mimicking Mad2, p31comet selectively binds the closed conformation of Mad2, termed C-Mad2, occupying the same interface that normally contacts BubR1 and therefore competitively extracting BubR1 from MCC. Together with AAA+
Ref: Alfieri et al., TRIP13-p31comet mechanism in MCC disassembly, Nature Communications 2018; Musacchio, SAC silencing, Curr Biol.