Figure 3.

Lipid requirement for AP-1 recruitment to peptidoliposomes. (A) Three percent of the indicated lipid was incorporated into PC peptidoliposomes exposing Lamp1Y. After incubation with a mixed adaptor preparation and with myristoylated ARF1·GMP-PNP, fractions I and IV of a flotation gradient were analyzed by immunoblotting. PIPs indicates a commercial mixture of phosphoinositides. (B) Two percent of PI-monophosphates and 1% of PI-bis- and trisphosphates were incorporated into PC peptidoliposomes exposing Lamp1Y and analyzed as in A. (C) The recruitment of AP-1 and ARF1 to liposomes containing different phosphoinositides (2% of PI-monophosphates and 1% of PI-bis- and trisphosphates) were densitometrically quantified. The amount recovered in fraction I is expressed in percent of the total in fractions I plus IV. The average and SDs of at least three experiments, including those shown in B, are presented.