Extracellular cAMP
cAMP

Extracellular cAMP may act as a signal in multiple environments.

The best studied model is Dictyostelium discoideum

Computational modelling suggests dynamic interactions between Ca2+, IP3 and G protein-coupled modules are key to robust Dictyostelium aggregation. 2009
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Three modules interconnected support our model for cAMP oscillations in Dictyostelium.
Close interdependence between the Ca2+, IP3 and G protein-coupled modules

1. Ca2+ is regulated by a number of proteins including IP3 channels and Ca2+ pumps on both basal and ER membranes
2. IP3 is synthesized by PLC in response to cAMPe dependent cAR1 activation
3. Extracellular cAMP binding to cAR1 activates ERK2, PLC and ACA via the G-protein subunits. cAMPi produced by ACA activates PKA which phosphorylates and thereby inhibits ERK2 as well as ACA via the cAR1/G-protein pathway.

Dynamic localization of G proteins in Dictyostelium discoideum, 2009