Polypeptide toxins and many antibacterial peptides, such as colicins or hemolysins, and certain proteins involved in apoptosis, are sometimes considered a separate category.
Toksin polipeptida dan banyak peptida antibakterial, seperti kolisin dan hemolisin, serta berbagai protein yang terlibat dalam apoptosis, terkadang dipertimbangkan pada kategori terpisah.