Caveolins and cellular cholesterol balance

Caveolins are major integral membrane components of caveolae. Over the last few years, evidence has accumulated for a close link between caveolin. cav eolae. and the regulation of cellular cholesterol levels. However, the exac t role of caveolin in this process, the intracellular trafficking routes fo llowed by caveolin/cholesterol complexes, and the relationship of caveolin- cholesterol to other caveolin-mediated processes such as signal transductio n have remained unclear. Recent findings from a number of systems suggest t hat specific signaling pathways require precise regulation of cellular chol esterol. Here we review evidence for caveolin regulation of cholesterol tra nsport and consider how this may relate to signal transduction.