Protein subunits are the building blocks of proteins. They come in various forms and play different roles in the synthesis and functioning of proteins. Synonyms for protein subunit include polypeptide chain, peptide chain, amino acid chain, protein component, protein fragment, protein moiety, protein unit, and protein building block. These terms are often used interchangeably to describe the structure and function of proteins. Understanding the various synonyms for protein subunits can help in the study and interpretation of protein structures and functions. Overall, protein subunits are essential components of many biological processes and have numerous applications in biotechnology and medicine.