A membrane coat found on coated pits and some coated vesicles; consists of polymerized clathrin triskelions, each comprising three clathrin heavy chains and three clathrin light chains, linked to the membrane via one of the AP adaptor complexes. [ http://www.ncbi.nlm.nih.gov/pubmed/11252894 http://www.ncbi.nlm.nih.gov/pubmed/9531549 ]