Proteins can function as
1. Biological Catalysts: enzymes that decrease the activation energy of a reaction and facilitate the progression of chemical reactions
2. Hormones: proteins can function as hormones, normally produced by a gland. Hormones act as chemical messages by binding to a specific receptor and activate a particular cellular pathway.
3. Channels/Pumps: proteins can comprise of strucrures located in the cell lipid bilayer. They allow for different types of molecules and compounds to exit or enter a cell.
4. Structural proteins: These proteins are found in different tissues in our body but also comprise protein structures of prokaryotic/eukaryotic cells such as the flagellum, used for cell motility. Structural proteins can also be a part of human tissues, including keratin found on nails and hair cuticles.