Hydrophilic Signals
Hydrophilic Signals. This topic focuses on:
- Signal transduction
- Insulin and the recruitment of GLUT4.
Overview
Signal transduction
Hydrophilic signalling molecules, such as peptide hormones and neurotransmitters, are not lipid soluble. Hydrophilic signals cannot cross the hydrophobic part of the plasma membrane, they must instead bind to transmembrane receptor molecules and do not enter the cytosol. These transmembrane proteins change conformation when the signal ligand binds to the extracellular cell surface; the signal molecule does not enter the cell but the signal is transduced across the plasma membrane. This means that the behaviour of the cell changes in response to the external binding of the signal molecule to the receptor molecule. The extracellular ligand-binding event is converted into intracellular signals.
For more on this topic, have a look at our CfE Advanced Higher Biology Study Guide – New Edition, pp. 36–37.
Related Videos
Watch these animations about insulin, insulin receptors and diabetes:
Another:
Thoughts
Since the 1923 Nobel Prize for medicine was awarded to Banting and Macleod, many Nobel prizes have been awarded for research into aspects of cell signalling. To get a flavour of some of the challenges, rivalries and successes involved in the discovery of insulin, watch the feature film Glory Enough for All.