Autophagy of ferritin incorporated into the cytosol of Hela cells by liposomes.

Ferritin was trapped in negatively charged liposomes consisting of phosphatidyl choline and phosphatidyl serine in a molar ratio of 9:1. Unilamellar vesicles were prepared by ultrasonic treatment. HeLa cells were incubated with these liposomes for 2h and chased for 0, 2, 14 and 20 h. The migration pathway of ferritin in the cells was followed by quantitative electron microscopy. Ferritin was detected exclusively in cytosol and lysosomes. Evidence is presented that free ferritin in cytosol enters lysosomes.