Fig. 4.

The cholesteryl moiety of native ShhN (ShhN_n). a Comparison of the EM maps for our Ptch1–ShhN_p and the recently published Ptch1*–ShhN_n (EMDB code EMD-8955) reveals an extra density of ShhN_n in the Ptch1*–ShhN_n map that protrudes into the extracellular steroid binding site (ESBS) of Ptch1*-P. The extra density is highlighted in pink. A zoomed-up cut-open view of the C-terminus of ShhN_n (ribbon representation) into ECD1 is shown on the right. b Density corresponding to the C-terminal peptide (C7) and cholesteryl moiety of ShhN_n contoured at 3 σ. c, The accommodation of the cholesteryl moiety by ESBS. As described previously, ESBS is mainly constituted by helices α3/α6/α7, E loop and C loop of ECD1. The hydrophobic residues that constitute the pocket are shown as sticks. The cholesteryl moiety is shown as pink sphere