Regarding the Amazing Choreography of Clathrin Coats

The growth of contemporary cell biology is due in large part to technological advances. In the 1950s, electron micrographs of thin sections first provided unrivaled in situ views of the delicate intracellular architecture and fine structure of organelles, whereas new subcellular fractionation methods gave access to various biochemical components—especially proteins—enriched in different cellular fractions. A central tenet that emerged from these pioneering studies is that the intracellular biosynthetic and endocytic membrane systems of eukaryotic cells are functionally interconnected, and exchange of material between them often occurs in small (50–100 nm diameter), roughly spherical membranous transport vesicles. In electron micrographs, these vesicles are typically seen in close proximity to a membrane compartment and are frequently covered on their cytosolic face with a fuzzy proteinaceous coating. Subsequent technical advances facilitated further discovery and progress: genetic screens in model organisms and refinement of subcellular fractionation to facilitate cell-free reconstitution of transport reactions allowed the identification and purification of key regulatory and structural components. Persuasively, many of the genes discovered in genetic screens encoded the proteins purified biochemically. More recently, genome sequencing and proteomics efforts have bolstered the identification of sorting components, leading to long lists of evolutionarily conserved proteins that are involved in specific sorting operations at different membranes.