[Frontiers in Bioscience 7, d1653-1661, July 1, 2002]


D. Page Baluch and David G. Capco

Department of Biology, Molecular and Cellular Biology Program, Arizona State University, Tempe, Arizona 85287-1501


1. Abstract
2. Introduction
3. Cellular scaffolds as a mechanism underlying cellular polarity and co-localization of factors
4. Conversion of the egg to the zygote: A brief overview
5. Signaling factors associated with structural elements in the egg/zygote
5.1. Calcium/calmodulin-dependent protein kinase II and the metaphase/anaphase transition
5.2. CaM KII and the midzone microtubules
5.3. Interaction between CaM KII and MAP Kinase
6. Conclusion
7. Acknowledgment
8. References


Cellular scaffolds serve as structural components to which various elements of signal transduction pathways can be associated. The association of components on a scaffold can have several important functions, for example they can: 1) associate upstream regulatory components in a cascade that can increase the speed of response to a stimulus; 2) restrict access of substrates to enzymes associated with the scaffold; 3) permit cross talk between distinct signaling pathways, and; 4) aid in the establishment of cellular polarity. The conversion of the mammalian egg into the zygote requires many rapid alterations during a distinct time frame to mediate the biochemical and structural changes that occur. Cellular scaffolds provide a mechanism that can perform these rapid, highly orchestrated changes. They can permit interaction between distinct calcium-dependent pathways and also can provide a means for the calcium signal, that is initiated by fertilization, to act on calcium-independent pathways. This review considers various lines of evidence suggesting that in the mammalian egg, the meiotic spindle serves as a cellular scaffold that permits coordination among several signaling pathways essential for fertilization and the initiation of early development.