Various conformations of 12:0-monoSF in wtGLTP and GLTP mutants. (a, b) Comparative superpositions of 12:0 monoSF with 24:1 monoSF as bound to wtGLTP (a) versus D48V (b). Protein moieties are omitted after being used for superimpositioning. Sulfatide atoms are coloured red, blue and green for oxygen, nitrogen and sulfur, respectively. 12:0-monoSF C atoms and extraneous hydrocarbons found in the hydrophobic pocket are coloured magenta in wtGLTP and cyan in D48V; 24:1 monoSF C atoms are coloured light magenta and light cyan, respectively. (c) Comparative superposition of 12:0 monoSF conformations in wtGLTP and D48V. Colour codes are as in (a) and (b). (d–f) Dimeric arrangements of the sphingosine-out modes in wtGLTP (d), D48V (e) and A47D/D48V (f). Colour codes are as in (a) and (b), except for the C atoms of A47D/D48V, which are shown in white. Red and green semitransparent rectangles highlight the sphingosine chains of the left and right monomers, respectively.