Potocytosis

Potocytosis is a type of receptor-mediated endocytosis in which small molecules are transported across the plasma membrane of a cell. The molecules are transported by caveolae (rather than clathrin-coated vesicles) and are deposited directly into the cytosol.[1]

Like other types of receptor-mediated endocytosis, potocytosis typically begins when an extracellular ligand binds to a receptor protein on the surface of a cell, thus beginning the formation of an endocytotic vesicle. The ligand is usually of low molecular mass (e.g. vitamins), but some larger molecules (such as lipids) can also act as ligands.[1][2]

Mechanism

Lipid rafts in the plasma membrane act as membrane microdomains. They are enriched in cholesterol and sphingolipids and are involved potocytosis as the lateral compartmentalization of molecules. Caveolae are caveolin-1-enriched smooth invaginations found on these lipid rafts that contribute to transportation of molecules.[3] Potocytosis works by taking up material into caveolae at the surface of the cell. Glycosylphosphatidylinositol-anchored class of membrane proteins generate high concentrations of molecules. This may either be by releasing a receptor bound molecule, by converting molecules enzymatically or by releasing them from a carrier protein.[4]

References
  1. Widmaier, Eric P.; Hershel Raff; Kevin T. Strang (2008). Vander's Human Physiology, 11th Ed. McGraw-Hill. pp. 114. ISBN 978-0-07-304962-5.
  2. Mineo, C.; Anderson, R.G. (August 2001). "Potocytosis. Robert Feulgen Lecture". Histochem Cell Biology. 116 (2): 109–18. doi:10.1007/s004180100289. PMID 11685539.
  3. Lajoie, Patrick; Nabi, Ivan R. (2010). "Lipid rafts, caveolae, and their endocytosis". International Review of Cell and Molecular Biology. 282: 135–163. doi:10.1016/S1937-6448(10)82003-9. ISBN 9780123812568. ISSN 1937-6448. PMID 20630468.
  4. Anderson, R. G. (March 1993). "Potocytosis of small molecules and ions by caveolae". Trends in Cell Biology. 3 (3): 69–72. doi:10.1016/0962-8924(93)90065-9. ISSN 0962-8924. PMID 14731772.
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