Meta-Biol

• Pathways

cAMP is a known regulator of PKA activity and works by binding to the regulatory subunits and promoting dissociation of the tetramer, freeing the active catalytic subunits (reviewed in Sassone-Corsi, 2012). In the Hh pathway in the absence of ligand, cAMP levels increase in response to the recruitment of GPR161 to the ciliary base by TULP3 and the IFT-A retrograde complex (Mukhopadhyay et al, 2010; Mukhopadhyay et al, 2013). Activated PKA then initiates the phosphorylation cascade that regulates processing and/or degradation of the GLI proteins (reviewed in Briscoe and Therond, 2013; Mukhopadhyay and Rohatgi, 2014).