Main biochemical reactions involving diffusible molecules.

The primary second messengers (DAG, IP3) come from their precursor (PIP2), the secondary messenger (Ca2+) comes from the sensillar lymph or intracellular stores. The two main modulators, Ca2+-calmodulin (CaCaM) and activated protein kinase C (PKC*), come from their precursors (CaM and PKC) in the presence of DAG and Ca2+. PA is phosphatidic acid. Reaction numbers same as in Figures 2 and 3.