Protein storage is defined as which of the following?

• A. reserve of amino acids
• B. source of energy
• C. primary function is enzymatic
• D. regulation of metabolism

Answer: (A)

Proteins primarily serve as a reservoir of amino acids that can be mobilized when needed. This storage role means that, if dietary intake is insufficient or if the body needs amino acids to build new proteins or other nitrogen-containing compounds, proteins can be broken down to release those amino acids. This concept sets protein storage apart from energy storage, since fats (and to a lesser extent carbohydrates) are the main energy reserves. While proteins also carry out enzymatic functions and help regulate metabolism, those are separate roles from storing amino acids for future use. So the statement describing protein storage as a reserve of amino acids best captures its storage concept.