Figure 2.

The NaPCCP C2 domain is required for binding to PI3P-containing liposomes. Phosphatidylcholine-based liposomes were incubated with MBP∷NaPCCP or MBP∷C2del and centrifuged at 100,000g, and proteins in the supernatant (S) and liposome pellet (P) fractions were detected by immunostaining with anti-MBP. A, The C2 domain is required for PI3P binding. Left, Control liposomes containing PC alone; right, 95% PC + 5% PI3P. B, Calcium is not required for binding. Left, Incubation in 10 mm EGTA; right, incubation in 0.5 mm Ca²⁺. C, MBP∷NaPCCP incubated with liposomes containing 100% PC or 95% PC + 5% PI3P, PI4P, or PIP3 as shown.