Figure 8

Fusion of Cvt vesicles and autophagosomes with the lysosome/vacuole must be regulated. A: Vesicles that bud from a donor organelle are physically tethered to the organelle and prevented from prematurely fusing with the acceptor compartment. Coat proteins drive the curvature and budding of the vesicle and must be removed prior to the final fusion with the acceptor compartment. B: Cvt vesicles and autophagosomes may not form from a pre-existing organelle and accordingly are free to diffuse in the cytosol. Fusion prior to vesicle completion would not result in delivery of the cargo into the lumen of the acceptor compartment. C: Normally the Cvt vesicle and autophagosome are completed prior to fusion with the lysosome/vacuole. This results in delivery of the cargo into the lumen of the acceptor organelle. It is not known if coat proteins are involved in regulating this process.