The bubble's bend

ubbles are not reserved to the likes of champagne or beer. Our cells also sprout bubbles – or vesicles. Vesicles are formed by means of two cellular processes: exocytosis and endocytosis. The point of such bubbles in living organisms is to relieve the plasma membrane of a number of constituents. Be it to down regulate a pathway – by removing a given receptor from the plasma membrane for example – or to transport molecules from one side of a cell to another. One species of vesicle – the clathrin-coated vesicles – are particularly important in vesicle trafficking in endocytosis and in exocytosis. And in the process of endocytosis, one protein – epsin – has a major role in the initial steps of membrane budding.