(A) Residues that line the binding pocket are shown in yellow, and the sterol molecule is shown in green.
(B) Hydrogen bonds between residues of NPC1(NTD) and the hydroxyl groups of the sterol are denoted by gray dots. Residues involved in hydrogen bonds are colored yellow, and the sterol molecule is colored green. Nitrogen atoms are shown in blue, and oxygen atoms are shown in red. Water molecules are shown as red spheres.