insulin

Examples of insulin in the following topics:

• Hormonal Regulation of Metabolism

  • Insulin is produced by the beta cells of the pancreas, which are stimulated to release insulin as blood glucose levels rise (for example, after a meal is consumed).
  • As insulin binds to its target cell via insulin receptors and signal transduction, it triggers the cell to incorporate glucose transport proteins into its membrane.
  • It can be caused by low levels of insulin production by the beta cells of the pancreas, or by reduced sensitivity of tissue cells to insulin.
  • Oversecretion of insulin can cause hypoglycemia, low blood glucose levels.
  • In this way, insulin and glucagon work together to maintain homeostatic glucose levels .

• Pancreas

  • As an endocrine gland, the pancreas produces several important hormones,such as insulin and glucagon, which are secreted into the bloodstream to regulate blood sugar levels, along with other activities throughout the body.
  • The pancreatic islets contain two primary cell types: alpha cells, which produce the hormone glucagon, and beta cells, which produce the hormone insulin.
  • When blood glucose levels rise, such as after a meal, beta cells release insulin to lower blood glucose levels by increasing the rate of glucose uptake in most body cells, and by increasing glycogen synthesis in skeletal muscles and the liver.
  • The alpha and beta cells produce glucagon and insulin, respectively.

• Humoral, Hormonal, and Neural Stimuli

  • For example, a rise in blood glucose levels triggers the pancreatic release of insulin.
  • Insulin causes blood glucose levels to drop, which signals the pancreas to stop producing insulin.

• Production of Vaccines, Antibiotics, and Hormones

  • Recombinant DNA technology was used to produce large-scale quantities of human insulin (a hormone) in E. coli as early as 1978.
  • Previously, it was only possible to treat diabetes with pig insulin, which caused allergic reactions in humans because of differences in the gene product.

• Lipid-Derived, Amino Acid-Derived, and Peptide Hormones

  • Secreted peptides, such as insulin, are stored within vesicles in the cells which synthesize them.
  • They are then released in response to stimuli (e.g., as high blood glucose levels in the case of insulin).

• Hormonal Regulation of Growth

  • GH also stimulates, through another pathway, the production of insulin-like growth factor 1 (IGF-1), a hormone homologous to proinsulin.
  • Insulin-like growth factor 1 (IGF-1) is activated by growth hormone and also allows formation of new proteins in muscle cells and bone.

• Protein Structure

  • For example, the pancreatic hormone insulin has two polypeptide chains, A and B.
  • For example, insulin is a ball-shaped, globular protein that contains both hydrogen bonds and disulfide bonds that hold its two polypeptide chains together.
  • The A chain of insulin is 21 amino acids long and the B chain is 30 amino acids long, and each sequence is unique to the insulin protein.

• Hypersensitivities

  • Insulin-dependent (Type 1) diabetes mellitus arises from a destructive inflammatory TH1 response against insulin-producing cells of the pancreas.
  • Patients with this autoimmunity must be injected with insulin that originates from other sources.

• Biotechnology in Medicine

  • In 1978, Genentech joined a gene for insulin with a plasmid vector and put the resulting gene into a bacterium called Escherichia coli.
  • Insulin, widely used for the treatment of diabetes, was previously extracted from sheep and pigs.
  • The resulting genetically-engineered bacterium enabled the production of vast quantities of human insulin at low cost.

• Hormone Functions

  • Cellular recipients of a particular hormonal signal may be one of several cell types that reside within a number of different tissues, as is the case for insulin, which triggers a diverse range of systemic physiological effects.