Caveolae are the most abundant features of the plasma membrane of many vertebrate cells. The surface of adipocytes, skeletal muscle, and many other cell types is densely covered by these small invaginations. The major membrane proteins of caveolae are small integral membrane proteins called caveolins. Three caveolins are present in mammalian cells with caveolin-1 (CAV1) and caveolin-3 (CAV3) essential for caveolar formation in non-muscle and muscle cells respectively. We have investigated the conservation of caveolins and caveola formation through evolution and we have combined these studies with caveolin-induced caveola formation in caveolin-null fibroblasts, in a model bacterial system, and more recently in a cell-free system to derive a model for caveolin-induced membrane remodelling. In vertebrate cells, caveolins work together with lipid-binding peripheral membrane proteins termed cavins. We have shown that Cavin1/PTRF is essential for caveola formation. Cytosolic levels of Cavin1 are kept low under steady state conditions by ubiquitination and proteasomal degradation of a lipid-binding site which is exposed when Cavin1 is released from the membrane. However, in response to a number of stimuli the released cavins can interact with intracellular targets to trigger cellular responses. These results highlight a critical role for caveolae and the caveolin-cavin system as protective and stress signaling elements of the plasma membrane.