In Physiology it is the name of a molecule composed of amino acids that is indispensable for the body to function properly. It is essential in body structures such as skin and hair or substances such as enzymes, cytokines and antibodies.
Molecule present in cells, based on amino acids, and with elementary functions for life. The name has Greek origin, where 960; 961; 969; 964; 949; 953; 959; 962; ( prooteios ) means "fundamental, main".