Extended Data Figure 4. Interactions with the M5–M6 connector, interactions with active site arginine residues, and cross-section of the active site.

a, Interactions between the M5–M6 and M7–M8 connectors. The side chains of Glu141 (on M5) and Lys153 (on the M5–M6 connector) form hydrogen bonds (dashed lines) that cap the C-terminal end of M7 and the N-terminal end of M8, respectively. Portions of the amino acids involved are drawn as sticks. Parentheses indicate hydrogen bonds made with backbone atoms. The colouring is: carbon, gray; nitrogen, blue; oxygen, red. b, Hydrogen bonding network involving Arg173 and Arg246. Bonds (dashed lines) are made with surrounding amino acids (labeled sticks) and two water molecules (red spheres) in the active site. c, Cutaway view of the molecular surface of ICMT (gray), showing labeled regions of the active site. The view is approximately orthogonal to that shown in Fig. 2a. AdoHcy is drawn as sticks; approximate boundaries of the membrane are indicated by horizontal bars.