Insulin
Insulin is a hormone. Its main function is the regulation of blood sugar levels, by causing the liver and muscles to increase uptake of glucose [1]. Insulin is produced from a single gene which codes for the peptide proinsulin; a precursor molecule. Mutations in this gene can result in a faulty protein; causing type 1 diabetes or a possible predisposition to type 2 diabetes [2][3].
Insulin regulates the blood glucose levels in different ways. It enhances the glucose transport at a cellular level by stimulation of the glucose transporter (GLUT) family.
Insulin also has an effect on gene expression which is up or down regulated in the homeostasis process to maintain the optimum blood glucose levels.
Insulin is released by the beta-cells of the pancreas.
Insulin stimulates glycogen synthesis.
When blood sugar levels are high, insulin binds to a tyrosine kinase receptor. Binding of insulin triggers a phosphorylation cascade, preventing phosphorylation of glycogen synthase as this inactivates it's activity.