Insulin

• Binds to glycoprotein receptors on muscle/fat cells to increase glucose uptake, regulates blood glucose/sugar levels, “Storage” hormone (made in the Pancreas) and its amino acids have hydrophilic R groups (water-soluble)
• Their two polypeptide chains fold into a tertiary structure, joined by disulphide bonds, A chain begins with a section of alpha helix and B chain ends with a section of a beta-pleated sheet