Fig. 7.

A model for the regulation of Ci subcellular localization by Trn and Sufu in Hh signaling. In the absence of Hh, full-length Ci (Ci^FL) forms complexes with Sufu and Cos2/Fu, which retain Ci^FL in the cytoplasm by NLS masking and microtubule tethering. In addition, Ci^FL is converted into a truncated repressor form (Ci^R) through ubiquitin/proteasome-mediated proteolysis. In the presence of Hh, Ci dissociates from Cos2 and Sufu, and Trn binds the exposed PY-NLS of Ci to promote its nuclear translocation.