I love it when things really throw me for a loop. Like when I heard that Kim Kardashian earned a perfect SAT score and was accepted into Harvard. Okay, that’s not really true…but just imagine our collective “whaaaa?!” In science there are always things that flip your lid, and today’s image is from a paper that does just that. Clathrin-coated pit closure just got more interesting.**
Clathrin-mediated endocytosis is a process during which material is brought into the cell through pits coated with a clathrin lattice, which provides structure to the developing vesicle. Electron microscopy images of clathrin-coated pits show great detail about their structure, but can only provide snapshots of what occurs inside of the cell. A recent paper describes clathrin-coated pit closure using a technique that combines the imaging of structural detail seen in electron microscopy (in this case, called scanning ion conductance microscopy) with live confocal microscopy used to track fluorescently-tagged proteins. During conventional clathrin pit closure, the pit is closed and cleaved from flat membrane sheets. Shevchuk and colleagues, however, found that 70% of pits close using an alternative mechanism. In this mechanism, a membrane protrusion grew from one side of the clathrin pit and covered the pit to close it, as seen in the images above.
**Halvsies if this tagline prompts next summer’s blockbuster movie.
Shevchuk, A., Novak, P., Taylor, M., Diakonov, I., Ziyadeh-Isleem, A., Bitoun, M., Guicheney, P., Lab, M., Gorelik, J., Merrifield, C., Klenerman, D., & Korchev, Y. (2012). An alternative mechanism of clathrin-coated pit closure revealed by ion conductance microscopy originally published in the Journal of Cell Biology, 197 (4), 499-508 DOI: 10.1083/jcb.201109130