Bistability of PP2A-B55 and APC/C activity

In a collaboration with Julia Kamenz in the lab of Jim Ferrell at Stanford Univ., we demonstrate biochemically using Xenopus laevis egg extracts that the Cdk1-counteracting phosphatase PP2A-B55 and the APC/C function as a bistable switch, even when the bistability of Cdk1 activation is suppressed. In addition, Cdk1 regulates PP2A-B55 in a biphasic manner and APC. Our findings, which are published in Current Biology, suggest that changes in Cdk1 activity are permissive for mitotic entry and exit but that the changes in PP2A-B55 activity are the ultimate trigger. Very impressive experiments by Julia, who just started her own lab at the university of Groningen in the Netherlands, check it out: