Protein kinase assays for measuring MPF and MAPK activities in mouse and rat oocytes and early embryos.

Protein phosphorylation plays a pivotal role in cell cycle regulation. MPF (M-phase Promoting Factor) and MAPK (Mitogen-activated protein kinase) are two major kinases driving oocyte maturation and early embryonic divisions. Their activities can be measured experimentally with kinase assays that use specific exogenous substrates. The activities of MPF and MAPK are measured using histone H1 kinase and MBP (Myelin Basic Protein) kinase assays, respectively. Here, we describe detailed procedures for measuring these two activities in mouse and rat oocytes and in early mouse embryos. The assays we describe can be performed using very small amounts of biological material and produce clearly discernible measurements of histone H1 and MBP kinase activities.