Using definitions from Wikipedia, a protomer is defined as "the structural unit of an oligomeric protein. It is the smallest unit composed of at least two different protein chains that form a larger heterooligomer by association of two or more copies of this unit."
In terms of proteins, the term monomer may refer to the amino acid components. However, an oligomeric complex with one subunit can be called a monomer (according to the page on protein quarternary structure).
Are these two terms interchangeable?
