Along with carbohydrates, fats, and nucleic acids, proteins are the ‘building blocks of life’ with which all life is made.
What does Protein Do?
Protein has a large number of important functions in the human body—and in fact, the human body is about 45% protein. It’s an essential macromolecule without which our bodies would be unable to repair, regulate, or protect themselves.
Functions of Protein
Protein has a range of essential functions in the body, including the following:
- Required for building and repair of body tissues (including muscle)
- Enzymes, hormones, and many immune molecules are proteins
- Essential body processes such as water balancing, nutrient transport, and muscle contractions require protein to function.
- Protein is a source of energy.
- Protein helps keep skin, hair, and nails healthy.
- Protein, like most other essential nutrients, is absolutely crucial for overall good health.
So what does protein do?
Proteins are, in effect, the main actioners in cells and in an entire organism. Without proteins the most basic functions of life could not be carried out. Respiration, for example, requires muscle contractions, and muscle contractions require proteins.
Proteins as Enzymes
The function of proteins as enzymes is perhaps their best-known function. Enzymes are catalysts—they initiate a reaction between themselves and another protein, working on the molecule to change it in some way.
The enzyme, however, is itself unchanged at the end of the reaction.
Enzymes are responsible for catalyzing reactions in processes such as metabolism, DNA replication, and digestion.
In fact, enzymes are known to be involved in some 4,000 bodily reactions.
Proteins in Cellular Signaling and Molecular Transport
Cells signal one another for an enormous variety of reasons, the most basic of which is simply to coordinate cellular activities. Signaling is how cells communicate with one another, allowing such essential processes as the contraction of the heart muscle to take place.
Proteins are important in these processes due to their ability to bind other molecules—a protein produced by one cell may bind to a molecule produced by another, thus providing a chemical signal which allows the cells to provide information about their state. Proteins are also involved in molecular transport.
A prime example of this is the protein called hemoglobin, which binds iron molecules and transports them in the blood from the lungs to organs and tissues throughout the body.