In biology, caveolae (Latin for little caves) are small (50 - 100 nanometer) invaginations of the plasma membrane in many cell types, especially in endothelialcells and adipocytes.
Caveolae are one source of clathrin independent endocytosis involved in turnover of adhesive complexes.
Formation and maintenance of caveolae is primarily due to the proteincaveolin.
Caveolae are estimated to make-up an estimated 30-70% of the plasma membrane area in certain cells such as endothelialcells, adipocytes, or Type I pneumocytes.
Caveolae are generally considered to be "invaginated" lipid rafts primarily due to an enrichment in a family or proteins known as the caveolins.
Caveolae are highly enriched in cholesterol as compared to the bulk plasma membrane and Cav-1 binds this cholesterol with high affinity (estimated at 1 cholesterol molecule per caveolin molecule) (Murata et al., 1995; Thiele et al., 2000).
Caveolae are small plasmalemmal vesicles of distinct, flask-shaped morphology that are especially abundant on the surface of many endothelialcells.
Caveolae are formed through the oligomerization of its structural proteins, caveolin-1 and caveolin-2, to form distinctive coat appearing as bipolar-oriented, thin striations surrounding the bulb of the caveloa (Fig.
Caveolae have recently been found to be a pathway for transport of specific macromolecules from the circulating blood to the underlying tissue.
Caveolae are invaginated, active micro-domains in the plasma membrane and are believed to be involved in receptor-mediated uptake of small molecules, a process called potocytosis.
The results suggest that caveolae are crucial for insulin-regulated events in fat-storage cells and suggest that disruption of these structures could have consequences for the development of insulin resistance and diabetes mellitus.
Expression of caveolin in cells which normally lack caveolae was shown to cause de novo formation of surface pits with the exact morphological characteristics of caveolae.
to induce caveolae, and in the absence of Cav-1, the Cav-2 protein
Caveolae are aligned along actin filaments, which copurify with
In the wild-type sample (A), caveolae open to the lumen (L) of the blood vessel are indicated by small arrows; large arrows indicate internalized caveolae.
B, caveolae: the liquid-ordered and liquid-disordered phases are illustrated as in panel A.
caveolae (i.e., cytoplasmic caveolae in transit to the abluminal
In transcytosis, caveolae transport proteins from the luminal side of the endothelialcell to the interstitial compartment for subsequent uptake by underlying tissues.
Main panel: caveolae in a differentiated 3T3-L1 adipocyte labelled with an electron-dense marker to delineate the cell surface.
Note the uniform size and shape of caveolae (some are indicated by arrowheads) and the numerous caveolae around larger surface-connected vacuoles (asterisks).
In particular, Caveolae formation may not necessarily require forces to be applied by the cytoskeleton.
Our theoretical model is able to explain several features observed experimentally in caveolae, where proteins in the caveolin family are known to play a crucial role in the formation of caveolae buds.
These include (i) the formation of caveolae buds with sizes in the 100nm range (ii) that a fairly large variation of bud shape is expected (iii) that certain N and C termini deletion mutants result in vesicles that are an order of magnitude larger.
These include 1) fenstra, 2) a transcellular channel, 3) traditional caveolae, 4) plasmalemmal vesicles (fully invaginated, static caveolae), 5) a vesiculo-vacuolar organelle (a grapelike cluster of interconnected caveolae and vacuoles), 6) cavicles (mobile, internalized caveolae not associated with the plasma membrane), and 7) a caveosome (a slow moving, irregularly shaped, cytoplasmic organelle).
Caveolin-1 was purified by velocity gradient centrifugation from isolated murine lung caveolae.
Proteins copurifying with caveolae organelles were further partitioned into hydrophobic and hydrophilic fractions with the detergent Triton X-114, resolved by SDS-PAGE, and stained with Coomassie blue.
Caveolae and Caveolins in the Cardiovascular System -- Gratton et al. 94 (11): 1408 -- Circulation Research(Site not responding. Last check: 2007-09-17)
of caveolins and caveolae, and caveolin-1 in caveolae is a negative
Caveolae from luminal plasmalemma of rat lung endothelium: microdomains enriched in caveolin, Ca(2+)-ATPase, and inositol trisphosphate receptor.
Cholesteryl ester is transported from caveolae to internal membranes as part of a caveolin-annexin II lipid-protein complex.
