Every function in the living cell depends on proteins.

• Motion and locomotion of cells and organisms depends on contractile proteins.
• The catalysis of all biochemical reactions is done by enzymes, which contain protein.
• The structure of cells, and the extracellular matrix in which they are embedded, is largely made of protein. (Plants and many microbes depend more on carbohydrates, e.g., cellulose, for support, but these are synthesized by enzymes.)
• The transport of materials in body fluids depends of proteins.
• The receptors for hormones and other signalling molecules are proteins.
• Proteins are an essential nutrient for heterotrophs.
• The transcription factors that turn genes on and off to guide the differentiation of the cell and its later responsiveness to signals reaching it are proteins.
• and many more - proteins are truly the physical basis of life.

Foods that supply the body with protein include animal products, grains, legumes, and vegetables. Proteins from animal sources contain the essential amino acids. Proteins are changed to amino acids in the body. For detailed information regarding proteins to to this page.

Are you getting enough protein in your diet? A list of proteins found in food can be found here.