FIG. 9.
Suggested model for coupling of PKC activation and calcium signaling in host J774 cells after infection with L. monocytogenes. As described in the text, we suggest that PKC δ, calcium influx, and PKC β II activation are coupled and are initiated as a result of activity of two listerial proteins, LLO and PI-PLC. Activation of PKC β I did not require PI-PLC or elevated [Ca2+]i, and we suggest that it occurs as a result of the formation of DAG as a result of the action of host PLC on phosphatidylinositol 4,5-bisphosphate (PIP2) (12), yielding inositol 1,4,5-triphosphate (IP3).