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Organelle · single membrane

Lysosomes

Recycling centres

Lysosomes · Recycling centres

In view

Opened up, the dense lumen is digesting a worn-out piece of mitochondrion, and an autophagosome waits to fuse alongside. Proton pumps stud the membrane. Most lysosomes gather near the centrosome, and now and then one darts along a microtubule.

Acidic sacs holding more than 60 kinds of digestive enzyme. They break worn-out organelles, engulfed bacteria and big molecules down into building blocks the cell can reuse. Material reaches them through endosomes, from outside the cell, and through autophagosomes, double-membrane sacs that wrap up worn-out parts inside it.

Proton pumps hold their interior at pH 4.5–5, a few hundred times more acidic than the cytosol. The enzymes only work in acid, which protects the rest of the cell.

Size
≈ 0.3–0.5 µm
Per cell
50 – 1,000
pH inside
4.5 – 5.0
Enzymes
60+ acid hydrolases

Did you know?

Christian de Duve discovered lysosomes in 1955 (Nobel 1974). In 2016 Yoshinori Ohsumi won a Nobel for autophagy, the way cells feed their own parts to lysosomes.

Sources

  1. Lysosomal size matters · de Araujo et al. 2020 · Traffic
  2. The intriguing life of autophagosomes · Mijaljica et al. 2012 · Int J Mol Sci
  3. Cryo-EM structures of intact V-ATPase from bovine brain · Wang et al. 2020 · Nat Commun
  4. Mechanisms and functions of lysosome positioning · Pu et al. 2016 · J Cell Sci
  5. Lysosome transport as a function of lysosome diameter · Bandyopadhyay et al. 2014 · PLoS One
  6. Targeting lysosomes in human disease: from basic research to clinical applications · Cao et al. 2021 · Signal Transduct Target Ther
  7. Endosome maturation · Huotari & Helenius 2011 · EMBO J
  8. The Acid Gate in the Lysosome · Hu et al. 2023 · Autophagy
  9. What is the pH of a cell? · Milo & Phillips · Cell Biology by the Numbers
  10. 4.3 Eukaryotic Cells · OpenStax · Biology 2e
  11. Lysosome diameter in human mammary epithelial cell at pH 7.4 · BioNumbers · BNID 106078
  12. Number of lysosomes per cell · BioNumbers · BNID 107483
  13. The Nobel Prize in Physiology or Medicine 1974 · NobelPrize.org
  14. The Nobel Prize in Physiology or Medicine 2016 · NobelPrize.org

Made by Djordje Janjic · LinkedIn