Hedgehog Signaling: Is Smo a G Protein-Coupled Receptor? Melanie Philipp, Marc G. Caron  Current Biology  Volume 19, Issue 3, Pages R125-R127 (February 2009) DOI: 10.1016/j.cub.2008.12.010 Copyright © 2009 Elsevier Ltd Terms and Conditions

Figure 1 Two arms of Smo signal transduction. (A) Activation of Smo decreases the production of cAMP via inhibitory G proteins. PKA is inhibited and does not phosphorylate Gli. Thus, Gli is stabilized and able to initiate transcription. (B) Phosphorylation of active Smo by GRK2 prepares the association of Smo with β-arrestin 2. Subsequent interaction between β-arrestin 2 and Kif3A facilitates trafficking of Smo into primary cilia, possibly in vesicles. In the cilium, Smo signal transduction is initiated. Current Biology 2009 19, R125-R127DOI: (10.1016/j.cub.2008.12.010) Copyright © 2009 Elsevier Ltd Terms and Conditions