1. Structural proteins provide structural support to cells and tissues. Examples include collagen, keratin, and elastin. 2. Contractile proteins are involved in muscle contraction. Examples include actin and myosin. 3. Enzymatic proteins catalyze chemical reactions in the body. Examples include enzymes such as amylase, protease, and lipase. 4. Transport proteins transport molecules across cell membranes. Examples include ion channels and pumps, such as the sodium-potassium pump and the glucose transporter. 5. Hormonal proteins regulate various physiological processes in the body. Examples include insulin, growth hormone, and thyroid hormone. 6. Storage proteins store amino acids for later use. Examples include casein in milk and ferritin in the liver.