Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: 
Quaternary structure is a larger assembly of several polypeptide chains, now referred to as subunits of the protein. The quaternary structure is stabilized by the same interactions as the tertiary structure. Complexes of two or more polypeptides are called multimers. Specifically, a dimer contains two subunits, a trimer contains three subunits, and a tetramer contains four subunits.


Question: What structure is a larger assembly of several polypeptide chains that are now referred to as subunits of the protein?
quaternary structure
Quaternary structure.