Figure 2.

Structure of the Notum-ghrelin complex. (A) Cartoon presentation of the Notum-ghrelin complex structure. Notum is shown in cartoon (enzyme core in dark grey and lid domain in light grey); ghrelin serine-3 is shown as brown sticks with the octanoyl lipid coloured green. (B) |Fo–Fc| annealing omit electron density map contoured at 3 σ for the octanoyl lipid and ghrelin serine-3 (OCT/S3). (C) The Notum enzyme pocket is shown (green mesh) with surrounding residues denoted as brown sticks and balls. Octanoyl-linked ghrelin serine-3 is shown as grey sticks. (D) Comparison of the Notum enzyme pocket occupied with octanoyl (OCT, green), myristoleate (MYZ, light blue), and palmitoleic acid (PAM, cyan). The pocket is shown as a grey surface with 50% transparency. The cavity detection radius cut-off was set at 4 solvents. (E) Notum-ghrelin lipid interaction details. The Notum structure is shown as the Cα trace, the interaction residues are denoted as grey sticks (Ser 232 to Ala mutation in cyan), and the hydrogen bonds are represented by dashed yellow lines. (F) Comparison of the Notum residue Y129 side chain conformation in the Apo (cyan) and complex (grey) structures; hydrophobic interactions are shown as dashed lines.