Colocalization of CaM KII and MAP kinase on architectural elements of the mouse egg: potentiation of MAP kinase activity by CaM KII.

The conversion of the egg to a zygote requires the initiation of several signaling pathways that act in an orchestrated fashion to rapidly remodel the egg. Architectural elements within the egg can serve to localize components of these signaling pathways and colocalization of such components provides the opportunity for interaction between different signaling pathways. This study examines the localization as well as the state of activation of two different kinases, MAP kinase and calcium/calmodulin-dependent protein kinase II (CaM KII). The meiotic spindle serves as a site for enrichment of these kinases. However, activated MAP kinase and activated CaM KII exhibit a developmental stage-specific pattern of localization that represents a subset of the area occupied by the distribution of the total mass of MAP kinase and CaM KII. Suppression of CaM KII activity results in reduction in the amount of MAP kinase as well as a decreased level of activity of MAP kinase. Since CaM KII becomes active as a result of fertilization, the former kinase could serve to potentiate MAP kinase activity and the colocalization of these two kinases may facilitate such an interaction.