Question

Consider the following FRAP experiment testing the components of the MCC complex. Mps1=Mad2. For each experiment, one of the proteins was FRAPed then recovery was tested. The point was to figure out the affinity of each component for each other (e.g. which one disassembles first, second, etc). What is your conclusion? At which point does Cdc20 release from the complex? Mps1 Bub3 Integrated Fluorescence Intensity R. 240 0 75 300 180 Time (sec) 150 225 Time (sec) Cdc20 BubR1 Integrated Fluorescence Intensity 000 R-72 000120 Time (sec) Time (sec)

Answer 1

The fast kinetics of Cdc20, BubR1, Bub3and Mps1

The SAC protein Bub3 is a phospho-amino acid adaptor that forms structurally

it is also related stable complexes with functionally distinct paralogs named Bub1 and BubR1

Bub1 and BubR1 (also known as Mad3 in certain organisms) are paralogous proteins that fulfill different crucial functions in chromosome alignment on the mitotic spindle and in the spindle assembly checkpoint

At the half-lives of 1–3 s point for Cdc20 complex release