Question

Describe the signal transduction pathway with an Insulin receptor. Explain.

Answer 1

Physical or chemical signal transmission through a cell by a series of molecular events is known as signal transduction where a stimulus is converted into a response.

Glucose homeostasis is controlled by insulin transduction pathway. After meals (mainly carbohydrates), the blood glucose levels rise which triggers the islets of langerhans in the pancreas to secrets insulin. Glucose enters beta cell of islets of langerhans through GLUT-2 vesicles by passive diffusion. In beta cell glucokinase converts glucose to glucose-6-phosphate (G6P). G6P is oxidised and generate ATP which inhibits ATP sensitive potassium ion channel. The ion channel close. This triggers depolarisation of cell membrane and then cell membrane is stretched. The influx of Ca2+ ions open the voltage gated calcium channel. This stimulate the secretion of insulin in extracellular fluid, outside the beta cell & insulin enters into the blood stream. After the entering of insulin in blood stream insulin binds to glycoprotein receptor which brings a conformational change, which activate tyrosine kinase domain. Tyrosine kinase then activates another protein IRS (1-4) & then activation of the PI-3k is occurred. The activation of PI-3k triggers synthesis of lipids, proteins and glycogen. So the excess glucose is converted into glycogen.