G protein-linked signaling pathways control the developmental program of Dictyostelium.

The similarity of the signal transduction systems controlling early development in Dictyostelium with those mediating the action of hormones and neurotransmitters in mammals suggests that these strategies were quickly refined as eukaryotic cells began to communicate. These simple, genetically tractable organisms thus offer a great opportunity to elucidate these pathways further. Combinations of the null mutants are being studied to address questions of redundancy, cross-talk, and networking. Since cAR1, cAR2, G alpha 2, G beta, ACA, CRAC, PKA, and PDE are essential to the program, the capacity to rescue these phenotypes also serves as a convenient screen for functional mutations in these proteins. Finally, random mutagenesis by the recently developed method of restriction enzyme-mediated insertion provides a means to isolate new genes (Kuspa et al., 1992). The clear phenotypes of the null mutants observed so far indicate that the Dictyostelium developmental program can be used as a guide to isolate novel components of G protein-linked pathways.