Fig. 1.

Predicted and detected phosphorylation in Smo. A schematic diagram of Smo is shown, alongside specific residues within intracellular loop two and a portion of the C-terminal cytoplasmic tail. Identified phosphoserine/threonine residues in endogenous Smo purified from HhN-stimulated Drosophila S2 cells are marked with asterisks. Phosphopeptides were isolated from eight distinct regions, as designated (I–VIII). Residues within the consensus kinase recognition motifs shown for PKA (red) and CK1 (blue) are highlighted. One residue that may be phosphorylated by either CK1 or GSK3, depending on the priming phosphoresidue, is shown in green. Designations of CK1 and GSK3 target residues assume that all possible priming phosphorylation has occurred.