Clathrin is a protein that plays a major role in the formation of coated vesicles. Coated pits are regions of the cell membrane specialized in receptor-mediated endocytosis. Their cytoplasmic surface is coated with a bristlelike structure made of clathrin. During the first steps of endocytosis, clathrin-coated pits are internalized to form clathrin-coated vesicles which transport proteins from organelle to organelle