World Library  
Flag as Inappropriate
Email this Article


Article Id: WHEBN0000202174
Reproduction Date:

Title: Caveolae  
Author: World Heritage Encyclopedia
Language: English
Subject: Endocytosis, Smooth muscle tissue, Cavin, Channelosome, Cell anatomy
Publisher: World Heritage Encyclopedia


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]


  • Caveolins 1
  • Caveolar endocytosis 2
  • Other roles of caveolae 3
  • Inhibitors 4
  • See also 5
  • References 6
  • External links 7


Formation and maintenance of caveolae is primarily due to the protein 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

  • Caveolae can be used for entry to the cell by some pathogens and so they avoid degradation in lysosomes. However, some bacteria do not use typical caveolae but only caveolin-rich areas of the plasma membrane. The pathogens exploiting this endocytic pathway include viruses such as SV40 and polyoma virus and bacteria such as some strains of Escherichia coli, Pseudomonas aeruginosa and Porphyromonas gingivalis. [7]
  • Caveolae have a role in the cell signaling, too. Caveolins associate with some signaling molecules (e.g. eNOS) through their scaffolding domain and so they can regulate their signaling. Caveolae are also involved in regulation of channels and in calcium signaling. [7]
  • Caveolae also participate in lipid regulation. High levels of caveolin Cav1 are expressed in adipocytes. Caveolin associates with cholesterol, fatty acids and lipid droplets and is involved in its regulation. [7]
  • Caveolae can also serve as mechanosensors in various cell types. In endothelial cells, caveolae are involved in flow sensation. Chronic exposure to the flow stimulus leads to increased levels of caveolin Cav1 in plasma membrane, its phosphorylation, activation of eNOS signaling enzyme and to remodeling of blood vessels. In smooth-muscle cells, caveolin Cav1 has a role in stretch sensing which triggers cell-cycle progression. [7]


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.  
  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.  
  3. ^ Li X, Everson W, Smart E (2005). "Caveolae, lipid rafts, and vascular disease". Trends Cardiovasc Med 15 (3): 92–6.  
  4. ^ Pelkmans L (2005). "Secrets of caveolae- and lipid raft-mediated endocytosis revealed by mammalian viruses". Biochim Biophys Acta 1746 (3): 295–304.  
  5. ^ Caveolae at the US National Library of Medicine Medical Subject Headings (MeSH)
  6. ^ a b c d Lajoie, P. and I.R. Nabi, Lipid rafts, caveolae, and their endocytosis. Int Rev Cell Mol Biol, 2010. 282: p. 135-63.
  7. ^ a b c d e Parton, R.G. and K. Simons, The multiple faces of caveolae. Nature Reviews Molecular Cell Biology, 2007. 8(3): p. 185-94.

External links

  • Histology image: 21402loa – Histology Learning System at Boston University
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.