Figure 1. A) Cytosolic regulator of adenylyl cyclase (CRAC) regulates chemotaxis and adenylyl cyclase (ACA) activation. Cartoon depicts the series of events leading to the chemoattractant-mediated activation of CRAC in Dictyostelium. B) Streaming during Dictyostelium chemotaxis. Left panel, a picture of Dictyostelium cells as they migrate by aligning in a head-to-tail fashion. Right panel, a model depicting the proposed localized secretion of the chemoattractant cyclic AMP (cAMP), which attracts cells to the back of the cell in front of them. The pictures represent the cellular distribution of CRAC and ACA during this process. PH, pleckstrin homology; GFP, green fluorescent protein; YFP, yellow fluorescent protein.