Fig. 2.

MPEG1 interacts with negatively charged phospholipids via its MABP β-hairpin. a Structural superposition of the MPEG1 MABP domain (yellow) and the MVB12-associated β-prism (grey). The lipid-binding loop of the MVB12-associated β-prism maps to the MABP β-hairpin. The tip of both the MPEG1 β-hairpin and the MVB12 loop similarly contain a group of positively charged and hydrophobic residues. b MPEG1 displays broad specificity for lipids with negative charge. c 3.6 Å structure of MPEG1 bound to lipid membranes (subunits alternately coloured). A glycan moiety (indicated by an asterisk) is attached to TMH-2. The direction that the pore-forming β-hairpins are released to form a membrane spanning β-barrel is shown by an arrow. d Structural superposition of the MPEG1 monomer derived from the head-to-head assembly (coloured as in Fig. 1c), and the lipid bound form (grey). The predicted position of the transmembrane domain (absent in the structure) is shown (blue cylinder). The β-hairpin shifts ~24° in response to lipid interaction and the L-domain is disordered in the lipid bound form. The approximate position of the membrane is shown for reference