Opa60 promotes proteoliposome uptake into HeLa cells. HeLa cells were pulsed for 15 min with proteoliposomes, then chased in fresh medium without liposomes for 0, 1, 2, or 3 hrs. Liposome internalization efficiency (internal/surface fluorescence) was determined for control (A), CEACAM1 (B), and CEACAM3 (C) HeLa cells following exposure to Opa60 (black) and Opa(HV−) (red) proteoliposomes. Opa60 enhances proteoliposome uptake into HeLa cells compared to Opa(HV−), shown as higher Internal/Surface values. The increase or decrease in proteoliposome internalization efficiency from Opa(HV−) to Opa60 is shown as a percent of baseline Opa(HV−) proteoliposome efficiency on each graph. These values were plotted in (D), showing that as time increases, efficiency of Opa60 internalization when compared to Opa(HV−) internalization increases only within the context of CEACAM1 HeLa cells. Error bars represent 95% C.I.