What is the quaternary structure of a protein? Do all proteins have quaternary structure?
The quaternary protein structure is the spatial conformation due to interactions among polypeptide chains that form the protein. Only those proteins made of two or more polypeptide chains have quaternary structure. Insulin (two chains), hemoglobin (four chains) and the immunoglobulins (antibodies, four chains) are some examples of protein having quaternary structure.
