Helices sculpt membrane

摘要

Many proteins are carried within cells in bubble-like sacs. These are pinched off from membranes inside the cell, and it seems that the Sarlp protein is key in both starting and finishing this budding process. The cell contains a network of membrane-bound compartments that exchange proteins with each other and with the cell surface thanks to several haulage systems, each providing a specific link between one station and another. At the departure point, specialized 'coat' proteins wrap up a small areaof the lipid membrane, shaping it into a bulging 'bud' and gathering up proteins due to be transported inside it. The bud detaches from the membrane — a stage called fission — to form a bubble-like Vesicle' loaded with cargo. Lee et al.2 report in Cell that a coat protein called Sarlp, whose structure contains several a-helices, initiates buds for one type of vesicle by thrusting one of its helices into the membrane, causing it to balloon outwards.