The M-phase regulator known as MPF (Maturation Promoting Factor) consists of:
Experiments in amphibian oocytes and in yeast genetics converged upon identification of universal M-phase regulator historically called Maturation Promoting Factor for its ability to induce meiotic maturation when cytoplasm from M-phase cells injected into G2 oocytes. Molecular composition resolved as complex of catalytic subunit CDK1 originally named cdc2 or p34cdc2 and regulatory subunit Cyclin B. CDK1 provides serine-threonine kinase activity requiring activating phosphorylation on activation loop Thr161 by CAK complex CDK7-Cyclin H-MAT1 and removal of inhibitory phosphates Thr14 Tyr15 via
Ref: Nurse, Universal Control of Cell Division by CDK1-Cyclin B MPF, Nature 1990; Alberts et al., Molecular Biology of the Cell, Chapter 17, Discovery of MPF.