1s- Hydrophilic signalling molecules and transduction Flashcards
What do hydrophilic signalling molecules bind to?
They bind to transmembrane receptors and do not enter the cytosol
What are two examples of hydrophilic extracellular signalling molecules?
- peptide hormones
- neurotransmitters
What do transmembrane receptors do when the ligand binds to the extracellular face and what happens to the signal molecule that is produced?
The transmembrane receptor changes conformation and the signal molecule does not enter the cell but the signal is transduced across the plasma membrane
How do transmembrane receptors act as signal transducers?
By converting the extracellular ligand-binding event into intracellular signals, which alters the behavior of the cell
What do transduced hydrophilic signals often involve?
G-proteins or cascades of phosphorylation by kinase enzymes
What do G-proteins do?
Relay signals from activated receptors (receptors that have bound a signalling molecule) to target proteins such as enzymes and ion channels
What do phosphorylation cascades allow to?
More than one intracellular signalling pathway to be activated
What do phosphorylation cascades involve?
A series of events with one kinase activating the next in the sequence and so on
What can phosphorylation cascades result in?
The phosphorylation of many proteins as a result of the original signalling event
What does the binding of the peptide hormone insulin to its receptor result in?
An intracellular signalling cascade that triggers recruitment of GLUT4 glucose transporter proteins to the cell membrane of fat and muscle cells
What does the binding of insulin to its receptor cause to happen?
A conformation change that triggers phosphorylation of the receptor. This starts a phosphorylation cascade inside the cell , which eventually leads to GLUT4-containing vescicles being transported to the cell membrane
There are two types of diabetes mellitus; type 1 and type 2. What are they both caused by?
Type 1 = failure to produce insulin
Type 2 = loss of receptor function
What is type 2 diabetes generally associated with?
Obesity
Why is exercise beneficial for people with type 2 diabetes?
It triggers recruitment of GLUT4, which improves uptake of glucose to fat and muscle cells in those with type 2 diabetes
