Mitophagy Cycle Diagram

A mitophagy cycle diagram, four-stage circular layout in a stylised cell.

Stage 1 — Damage Sensing
- A healthy mitochondrion (left, drawn with intact inner membrane folds in green) loses membrane potential and becomes a "damaged mitochondrion" (drawn with broken folds in faded gray).
- PINK1 accumulates on the outer membrane, recruiting Parkin which ubiquitinates surface proteins.

Stage 2 — Cargo Recognition
- Autophagy receptors (e.g., NDP52, OPTN) bind the ubiquitinated mitochondrion via their UBA domain and bind LC3-II via their LIR motif on a forming phagophore.

Stage 3 — Engulfment
- A double-membrane phagophore wraps around the damaged mitochondrion, sealing into an autophagosome.

Stage 4 — Lysosomal Fusion & Degradation
- The autophagosome fuses with a lysosome (drawn with internal acidic-pH motif), forming an autolysosome that degrades the mitochondrion.
- Recycled amino acids and lipids exit the autolysosome, completing the cycle back to mitochondrial biogenesis.

Style: biomedical illustration, restrained palette (green for healthy, gray for damaged, navy and coral for vesicles), white background, suitable for cell biology journals.