What is the composition of protein hormones?

Protein hormones are primarily composed of long chains of linked amino acids, which form the basic structure of proteins. These chains can vary significantly in length and composition, leading to a diverse array of protein hormones that perform various functions in the body. The sequence and arrangement of amino acids in these chains determine the specific structure and function of each hormone.

While modified amino acids and short chains of amino acids can play roles in some biological molecules, they do not define protein hormones specifically. Cholesterol derivatives describe steroids, which are a different class of hormones altogether and do not include protein hormones. Thus, the correct composition of protein hormones directly corresponds to long chains of amino acids, which is fundamental to their identity and function in biological processes.