Caveolae: An alternative membrane transport compartment

Caveolae are omega-shaped invaginations of the plasma membrane with a diame ter of 50-100 nm. Caveolae invaginations can detach from the plasma membran e to form discrete functional caveolae vesicles within the cell cytoplasm. Caveolae are most prominent in adipocytes, fibroblasts, muscle cells (skele tal, smooth and cardiac), capillary endothelium and type I pneumocytes, alt hough other cell types also display these structures but at a lower numeric al density. The key structural and functional protein for caveolae is caveo lin. At the plasma membrane caveolae serve to compartmentalise and integrat e a wide range of signal transduction processes. Caveolae also serve transp ort functions including that of the vesicular internalisation of small mole cules by the process of potocytosis, and the endocytic and transcytotic mov ements of macromolecules. Opportunities exist for basic and applied investi gators working within the pharmaceutical sciences to exploit caveolae membr ane interactions with the aim to develop novel cellular or transcellular dr ug delivery strategies.