Clathrin adaptors really adapt.

The clathrin pathway is the principal route for receptor-mediated endocytosis and growth factor downregulation. Heterotetrameric clathrin adaptors directly link the clathrin coat with cargo transmembrane proteins that are sorted into coated pits and vesicles. A paper in this issue of Cell describes the atomic structure of the adaptor-protein 2 (AP-2) core, the portion that makes contacts with the membrane and cytosolic tails of cargo proteins.