The polymer of proteins is called a polypeptide. Proteins are polymers made up of monomers called amino acids. These amino acids are linked together by covalent bonds known as peptide bonds , forming long linear chains called polypeptides

. To elaborate:

• Amino acids are the building blocks (monomers) of proteins.
• When amino acids join through peptide bonds (formed by a dehydration synthesis reaction), they create polypeptides, which are the polymer form.
• A protein can consist of one or more polypeptide chains folded into a specific three-dimensional structure that determines its function.
• The terms polypeptide and protein are sometimes used interchangeably; however, technically, a polypeptide is the polymer chain of amino acids, and a protein is one or more polypeptides folded into a functional form

In summary, proteins are polymers of amino acids, and these polymers are called polypeptides.