Caveolae

In biology, caveolae (Latin for little caves) are small (50–100 nanometre) invaginations of the plasma membrane in many vertebrate cell types, especially in endothelial cells and adipocytes. Some cell types, like neurons, may completely lack caveolae.

These flask-shaped structures are rich in proteins as well as lipids such as cholesterol and sphingolipids and have several functions in signal transduction (Anderson, 1998). They are also believed to play a role in endocytosis, oncogenesis, and the uptake of pathogenic bacteria and certain viruses.

Caveolae are one source of clathrin-independent endocytosis involved in turnover of adhesive complexes.

Formation and maintenance of caveolae is primarily due to the protein caveolin. This protein has both a cytoplasmic C-terminus and a cytoplasmic N-terminus, linked together by a hydrophobic hairpin that is inserted into the membrane. The presence of caveolin leads to the local change in morphology of the membrane.

Because of their specific lipid content, caveolae are sometimes considered as a caveolin-positive subset of lipid rafts.