Module 11: Figure autophagy
Control of autophagy.
Autophagy is the large-scale degradation of cytoplasmic components. During an induction process, a membrane protrusion buds off from the ER and begins to enlarge (vesicle nucleation) to form a cup-shaped vesicle that then elongates and breaks away from the ER to form an isolation membrane that engulfs mitochondria and ribosomes to form an autophagic vacuole, which then fuses with a lysosome where degradation occurs. These membrane events are controlled by a variety of signalling pathways many of which are channelled through the target of rapamycin (TOR) to activate the induction processes. Another pathway depends on various signalling processes that are directed towards the class III PI 3-kinase hVPS34 to generate PtdIns3P that acts to control the process of vesicle nucleation. For further details of the way these signalling pathways control autophagy see Module 11: Figure autophagy signalling mechanisms.