Function of Proteins

Why Are Proteins Important?

Protein is a critical component of all cells and is involved in practically every function performed by them. They are important in the structural framework of cells and tissues as well as the immune system and transporting oxygen. Although the body doesn’t store extra protein, the body can use existing protein as a source of energy if necessary.

Building Blocks of the Body

Proteins are an integral part of every cell and tissue in the body. Without a source of protein, it would not be possible to grow, repair and replace the every tissues and organs in our body. The most recognized proteins for growth and repair are collagen, keratin, and fibrin. Collagen is the most abundant structural protein and is a main component of the connective tissue. Keratin is used to create hair and skin and fibrin is deposited around a wound after an injury.

Controls Cell Functions

The cells in our body performed many different functions and at different times. Which function and when it occurs is mainly determined by proteins called enzymes. Enzymes control or regulated the various chemical reactions that lead to a particular function. Without enzymes controlling the process, there would be no order to things and chaos would ensure.

Communicating With Cells

The body is made up of trillions of individual cells. If cells were not able to talk to and coordinate between themselves, complicated life could not exist. Proteins cross the layer surrounding cells (cell membrane), which allows for signals to travel between the outside to the inside of a cell. For example, when something touches or trigger a change in the part of the protein outside the cell, there is a change to the part of the protein inside the cell.

Transportation of Substances

Proteins are also very important for transporting substances in the body. For example, oxygen in the lungs binds to the main protein of red blood cells, called hemoglobin, and is transported around the body in blood. When the oxygen is deposited in some tissue, it picks up carbon dioxide and returns it to the lungs. Another example is protein channels in cells that particles (including electrolytes and water) travel into and out of the cells. Albumin, the largest single protein in the blood, is known to transport many particles including medications as well.

Consumed as Energy

Most energy used by cells in the body is supplied by breaking down the body’s reserves of fats (or lipids) and sugars (or carbohydrates). Because the body is limited in its ability to store extra carbohydrates or protein in the diet, excess calories from one’s diet is stored primarily as fat. This happens because the body can break down carbohydrates and protein and converted it to fat. Since most people take in more protein than they need for growth and repair, the excess protein is broken down to amino acids and then converted to sugars or fats.

When somebody is starving, they normally use up all the carbohydrates stores within one day. After that, they started to mobilize their fat and use it as the primary source of energy. When the fat is all gone, the body has no choice but to break down protein from the muscles and other organs. This is usually done only as a last resort because of the protein loss disrupts normal functioning and can lead to death.

Source

• Daignault et al. “Nutritional Requirements of Healthy Adults.” Handbook of Nutrition and the Kidney. Ed William Mitch and Saulo Klahr. Philidelphia: Lippincott Williams & Wilkins, 2005. 1-28.