has part has part has_part complex of molecules complex of molecules cellular_component protein-containing complex This is not covalently bonded, which conflicts with changes to the parent definition. protein complex protein-containing complex A stable assembly of two or more macromolecules, i.e. proteins, nucleic acids, carbohydrates or lipids, in which at least one component is a protein and the constituent parts function together. A ribosome is a protein complex. protein