FIGURE 15-30 Activation of CREB transcription factor following ligand binding to G_αs-coupled GPCRs. Receptor stimulation 1 leads to activation of PKA 2. Catalytic subunits of PKA translocate to the nucleus 3 and there phosphorylate and activate the CREB transcription factor 4. Phosphorylated CREB associates with the co-activator CBP/P300 5 and other proteins to stimulate transcription of the various target genes controlled by a CRE regulatory element. See K. A. Lee and N. Masson, 1993, Biochim. Biophys. Acta 1174:221, and D. Parker et al., 1996, Mol. Cell Biol. 16(2):694.