Figure 1. Potential roles of the Atg12–Atg5-Atg16 complex during autophagosome formation. The association of the Atg12–Atg5 conjugate with Atg16 unmasks a membrane-binding site in Atg5 and allows it to bind to phagophore precursors. Due to the dimerization of Atg16, each molecule of the Atg12–Atg5-Atg16 complex contains two molecules of Atg5 enabling Atg12–Atg5-Atg16 to tether vesicles. Atg12 stimulates this tethering activity. In addition, Atg16-dependent membrane localization of Atg12 is required to bring Atg8-bound Atg3 to the membrane. This in turn facilitates the conjugation of Atg8 to PE.