Clathrin is the major protein of the polyhedral coat of coated pits and vesicles. Two different adapter protein complexes link the clathrin lattice either to the plasma membrane or to the trans-Golgi network (By similarity). Clathrin triskelions, composed of 3 heavy chains and 3 light chains, are the basic subunits of the clathrin coat (By similarity). In the presence of light chains, hub assembly is influenced by both the pH and the concentration of calcium (Probable). May interact with OCRL (By similarity). Interacts with AFTPH/aftiphilin (PubMed:15758025). Cytoplasmic face of coated pits and vesicles. Maximal levels in skeletal muscle. High levels in heart and testis. Low expression detected in all other tissues. The C-terminal third of the heavy chains forms the hub of the triskelion. This region contains the trimerization domain and the light-chain binding domain involved in the assembly of the clathrin lattice. The N-terminal seven-bladed beta-propeller is formed by WD40-like repeats, and projects inward from the polyhedral outer clathrin coat. It constitutes a major protein-protein interaction node (By similarity). Belongs to the clathrin heavy chain family.