There’s a song on the radio that you just love right now. You’re not sure what it is about the song that you love…the catchy chorus, the singer’s silky voice, the booming bass line, the touch of pan flute, whatever. If you’re musically-inclined, you start teasing the song apart in your head until you finally realize what it is (always, it’s the pan flute!). Knowing how to tease a complex problem apart is a key skill for any scientist, and today’s image is from a paper that pares down clathrin-coated pits to their bare minimum.
Clathrin coats are assembled cages of the scaffolding protein clathrin. These scaffolds deform a planar membrane into a curved membrane that is able to bud off during the uptake of material into the cell, a process called endocytosis. It was previously thought that clathrin-associated proteins helped to induce curvature in the membrane, but recently a group finds otherwise, in a study that describes the minimum requirements for clathrin-coated bud formation. In this paper, Dannhauser and Ungewickell monitored bud and vesicle formation using a cell-free system composed of brain lipids that artificially form vesicles called liposomes. They found that clathrin alone is sufficient to generate buds in a lipid membrane. In the images above, buds and vesicles were formed when liposomes were in the presence of clathrin, but lacking any other proteins able to induce membrane curvature. Many vesicles were, in fact, still attached to the liposomes via narrow membrane necks (arrows).
Philip N. Dannhauser, & Ernst J. Ungewickell (2012). Reconstitution of clathrin-coated bud and vesicle formation with minimal components Nature Cell Biology, 14 (6), 634-639 : 10.1038/ncb2478
Adapted by permission from Macmillan Publishers Ltd, copyright ©2012