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. 2019 Mar 19;116(8):1495–1506. doi: 10.1016/j.bpj.2019.03.003

Figure 3.

Figure 3

PS asymmetry is stable for days postexchange and in the presence of pHLIP. (A) Stability of asymmetric vesicles was monitored for a period of 4 d post exchange. Day zero indicates the level of PS in the outer leaflet before exchange. Days 1–4 display the level of asymmetry post exchange. Both GC/MS and Annexin V-568 were used to determine the level of membrane asymmetry independently. Error bars represent the measurement uncertainty for each day obtained from replicates. (B) Shown is a comparison of PS levels in the outer leaflet of asymmetric vesicles incubated in the presence and absence of pHLIP. Here, pHLIP was incubated with asymmetric vesicles in both State II and III within the same sample by changing the pH after a given period of time. The symmetric vesicle PS level is before exchange, and the asymmetric vesicle level is post exchange. Here, the symmetric PS level was ∼12%. The inclusion of pHLIP in the asymmetric vesicles does not lead to a loss of membrane asymmetry over a 3-h period post addition of pHLIP. ∗∗∗p < 0.005; NS, no significance. n = 3–4. Error bars are SD.