The Quaternary Structure is the interaction that the different proteins have with one another to form a more complex protein
A Qauternary Structure is made up of several polypeptide chains (subunits) which can be either similar (homo) or different (hetero), and when they come together they give the protein its quaternary structure.
Two subunits is called a dimer, three subunits is called a trimer and four subunits a tetramer.
In order for the structure to have its particular shape it need to hold the peptide chains with a variety of interactions such as H-bonding, salt bridges and disulfide bonds.
A triple Helix structure has three individual strands of proteins that are bound to each other with hydrogen bonds
An example of a quaternary structure is hemoglobin in our bodies, which transports oxygen through and from our blood, and Rubisco which used in ATP synthase.