Hydrophilic Signals And Transduction Flashcards
What do Hydrophobic signalling molecules bind to?
Transmembrane receptors and they do not enter the cytosol
What are some examples of hydrophilic extracellular signalling molecules?
Peptide hormones and neurotransmitters
When does the transmembrane molecule go through a conformational change?
When the ligand binds to the extracellular molecule
Does the signal molecule enter the cell?
No but the signal is transduced across the plasma membrane.
How do the transmembrane receptor act as signal transducers?
By converting the extracellular ligandbinding event into intracellular signals which alter the behaviour of the cell
What do transduced hydrophilic signals often involve?
G-proteins or cascade of phosphorylation by kinase enzyme
What does G-protein do?
They relay signals from activated receptors to target proteins such as enzymes and ion channels
What is an active protein?
They are receptors that have bound a signalling molecule
What does a phosphorylation cascades allow to be activated?
more than one intracellular signalling pathway to be activated
What does a phosphorylation cascades involve?
It involves a series of events with one kinase activating the next in the sequence and so on. Phosphorylation cascades can 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 receptors cause?
A conformational change that triggers phosphorylation of the receptors. This starts a phosphorylation cascade inside the cell which eventually leads to GLUT4 containing vesicles being transported to the cell membrane
How can diabetes mellitus be caused by?
By failure to produce insulin (type 1) or loss of receptor function (type 2)
What is type 2 generally associated with?
Obesity
What does exercise trigger the recruitment of?
It triggers the recruitment of GLUT4 so exercise can improve uptake of glucose to fat and muscle cells in subjects with type 2
