PaAP is abundant and active in vesicles from CF strains and promotes the association of P. aeruginosa vesicles with lung cells. A, Purified vesicles (approximately 10 μg) were TCA-precipitated and analyzed using SDS-PAGE and Coomassie staining. Previously identified proteins in PA01 vesicles and CF2 vesicles are indicated, and (*) highlights the lower molecular weight form of OprD found in PA01 . The migration of molecular weight standards is indicated (kDa). B and C, Purified vesicles from the indicated strains (2.5 μg protein/well) were incubated (24 h, 37°C) with confluent monolayers of A549 cells (5 × 104/well) and vesicle-host cell association was compared with S470 vesicle association within each experimental set. SEM is indicated; n = 2 in triplicate.