Binding of the MA domain of HIV-1 Gag to PI(4,5)P2. A. The N-terminal myristate (dark green) is sequestered in the globular core of MA. The MA highly basic region (blue patch), CA (red), NC and p6 (dark blue) are shown. B. Upon binding of MA to PI(4,5)P2 in the inner leaflet of the lipid bilayer, the myristic acid (dark green) flips out from MA into the exposed conformation and inserts into the lipid bilayer. According to this model, the 2′-acyl chain (purple) of PI(4,5)P2 is extruded from the membrane and docks into a groove in MA. C. Structure of PI(4,5)P2. The two phosphates (red) are attached to the inositol ring (yellow) at position 4 and 5. The 2′-acyl chain (violet) is unsaturated and kinked and the 1′-acyl chain is saturated. Reprinted with permission from Freed, 2006, (Freed, 2006). Copyright 2006, The National Academy of Sciences of the USA. Based on the data of (Saad et al., 2006).