Module 8: Figure PLC sequestration hypothesis
The role of phospholipase Cζ (PLCζ) in controlling Ca2+ signalling and early cell cycle events following fertilization: the PLCζ sequestration hypothesis.
At the time of fertilization, the sperm inject phospholipase Cζ (PLCζ) into the oocyte to initiate the Ca2+ oscillations that function to complete meiosis by extruding the second polar body and forming the pronuclei. The latter marks the point where Ca2+ oscillations cease. As the zygote approaches the first mitosis, nuclear envelope breakdown releases PLCζ, which once again initiates the Ca2+ signalling that may drive certain aspects of mitosis. When the nuclei reform within the two daughter cells, they resequester PLCζ, which is taken out of circulation causing the spikes to cease. (Summary of work described in Marangos et al. 2003.)