Answer
The answer is No. Not all proteins have a quaternary structures. Quaternary structures are formed by the interactions and the interrelations between two or more protein sub-units (polypeptide chains) . Therefore, single chain proteins like parathyroid hormone by definition cannot have quaternary structures.
Work Step by Step
Globular proteins like hemoglobin have quaternary structures. Fibrous prote1ns like collagen and keratin do not have quaternary structures