A G-protein linked signal transduction mechanism controls chemotaxis in eukaryotes. During development the social amoeba Dictyostelium directs chemotaxis towards external cAMP with its G-protein linked cAMP receptor. Interactions of the receptor and G-proteins transduce the chemotactic signal to the interior of the cell and eventually to the motor apparatus. Phosphorylation of the cAMP receptor has been correlated with the cell's ability to adapt to the external cAMP signal. This signal transduction pathway may help to explain the ability of eukaryotic cells to orient within a chemical gradient by the use of spatial cues.