In biology, caveolae (Latin for "little caves"; singular, caveola), which are a special type of lipid raft, are small (50–100 nanometer) invaginations of the plasma membrane in many vertebrate cell types, especially in endothelial cells and adipocytes.

These flask-shaped structures are rich in proteins as well as lipids such as cholesterol and sphingolipids and have several functions in signal transduction.[1] They are also believed to play a role in endocytosis, oncogenesis, and the uptake of pathogenic bacteria and certain viruses.[2][3][4]


Formation and maintenance of caveolae is primarily due to the caveolin,[5] a 21 kD protein. There are three homologous genes of caveolin expressed in mammalian cells: Cav1, Cav2 and Cav3. These proteins have a common topology: cytoplasmic N-terminus with scaffolding domain, long hairpin transmembrane domain and cytoplasmic C-terminus. Caveolins are synthesized as monomers and transported to the Golgi apparatus. During their subsequent transport through the secretory pathway, caveolins associate with lipid rafts and form oligomers (14-16 molecules). These oligomerized caveolins form the caveolae. The presence of caveolin leads to a local change in morphology of the membrane.[6]

Caveolar endocytosis

Caveolae are one source of clathrin-independent raft-dependent endocytosis. The ability of caveolins to oligomerize due to their oligomerization domains is necessary for formation of caveolar endocytic vesicles. The oligomerization leads to formation of caveolin-rich microdomains in the plasma membrane. Increased levels of cholesterol and insertion of scaffolding domain of caveolins to the plasma membrane then lead to expansion of the caveolar invagination and to formation of endocytic vesicle. Fission of the vesicle from the plasma membrane is then mediated by GTPase dynamin II which is localized at the neck of the budding vesicle. The released caveolar vesicle can fuse with early endosome or caveosome. The caveosome is an endosomal compartment with neutral pH which does not have early endosomal markers, however, contains molecules internalized by the caveolar endocytosis.[6][7]

This type of endocytosis is used for example for transcytosis of albumin in endothelial cells or for internalization of the insulin receptor in primary adipocytes.[6]

Other roles of caveolae


Some known inhibitors of the caveolae pathway are Filipin III, Genistein and Nystatin.[6]

See also


  1. Anderson RG (1998). "The caveolae membrane system". Annu. Rev. Biochem. 67: 199–225. doi:10.1146/annurev.biochem.67.1.199. PMID 9759488.
  2. Frank P, Lisanti M (2004). "Caveolin-1 and caveolae in atherosclerosis: differential roles in fatty streak formation and neointimal hyperplasia". Current Opinion in Lipidology. 15 (5): 523–9. doi:10.1097/00041433-200410000-00005. PMID 15361787.
  3. Li X, Everson W, Smart E (2005). "Caveolae, lipid rafts, and vascular disease". Trends Cardiovasc Med. 15 (3): 92–6. doi:10.1016/j.tcm.2005.04.001. PMID 16039968.
  4. Pelkmans L (2005). "Secrets of caveolae- and lipid raft-mediated endocytosis revealed by mammalian viruses". Biochim Biophys Acta. 1746 (3): 295–304. doi:10.1016/j.bbamcr.2005.06.009. PMID 16126288.
  5. Caveolae at the US National Library of Medicine Medical Subject Headings (MeSH)
  6. 1 2 3 4 Lajoie, P. and I.R. Nabi, Lipid rafts, caveolae, and their endocytosis. Int Rev Cell Mol Biol, 2010. 282: p. 135-63.
  7. 1 2 3 4 5 Parton, R.G. and K. Simons, The multiple faces of caveolae. Nature Reviews Molecular Cell Biology, 2007. 8(3): p. 185-94.

External links

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