LAUSR

GPCR signaling is the most prevailing molecular mechanism for detecting ambient signals in eukaryotes. Chemotactic cells use GPCR signaling to process chemical cues for directional migration over a broad concentration range and with high sensitivity. Dictyostelium discoideum is a classical model, in which the molecular mechanism underlying eukaryotic chemotaxis has been well studied. Here, we describe protocols to evaluate the spatiotemporal chemotactic responses of Dictyostelium discoideum by different microscopic observations combined with biochemical assays. First, two different chemotaxis assays are presented to measure the dynamic concentration ranges for different cell strains or chemotactic parameters. Next, live-cell imaging and biochemical assays are provided to detect the activities of GPCR and its partner heterotrimeric G proteins upon chemoattractant stimulation. Finally, a method for detecting how a cell deciphers chemical gradients is described.