Insulin signal transduction pathway is secreted after glucose enters the beta cell and that triggers several other processes in a chain reaction. While insulin is secreted by the pancreas to lower blood glucose levels, glucagon is secreted to raise blood glucose levels. This is why glucagon has been known for decades as a counter-regulatory hormone. When blood glucose levels are low, the pancreas secretes glucagon, which in turn causes the liver to convert stored glycogen polymers into glucose monomers, which is then released into the blood. This process is called glycogenolysis. Liver cells, or hepatocytes, have glucagon receptors which allow for glucagon to attach
Glycogen found that muscular tissue also contains glycogen. The empirical formula for glycogen of () was established by Kekulé in 1858. Glycogen synthesis is, unlike its breakdown, endergonic—it requires the input of energy. Energy for glycogen synthesis comes from uridine triphosphate (UTP), which reacts with glucose-1-phosphate, forming UDP-glucose, in a reaction catalysed by UTP—glucose-1-phosphate uridylyltransferase. Glycogen is synthesized from monomers of UDP-glucose initially by the protein glycogenin, which has two tyrosine anchors for the reducing end of glycogen, since glycogenin is a homodimer. After about eight glucose molecules have been added to a tyrosine residue, the enzyme glycogen synthase progressively lengthens