There are seven main types of proteins:
- Antibodies: These proteins are produced by the immune system to fight off infections. They bind to foreign invaders, such as bacteria and viruses, and mark them for destruction by other immune cells.
- Contractile proteins: These proteins are responsible for muscle contraction. They include actin and myosin, which work together to allow muscles to shorten and lengthen.
- Enzymes: These proteins act as catalysts, speeding up chemical reactions in the body. They play a role in everything from digestion to DNA replication.
- Hormonal proteins: These proteins act as chemical messengers, carrying signals throughout the body. Examples include insulin, which regulates blood sugar levels, and growth hormone, which promotes growth and development.
- Structural proteins: These proteins provide support and structure to cells, tissues, and organs. Examples include collagen, which is found in skin, bones, and tendons, and keratin, which is found in hair, nails, and skin.
- Storage proteins: These proteins store amino acids for later use. An example is casein, the main protein found in milk, which provides infants with a source of amino acids.
- Transport proteins: These proteins carry molecules, such as oxygen and nutrients, around the body. Hemoglobin, which carries oxygen in the blood, is an example of a transport protein.
