Lecture 6 - Signalling Pathways
20 multiple choice questions & short/long answer questions (20 marks)
1) what is "signal transduction" and why is it significant?
-cellular response begins with binding of signal to receipt
(how the signal is trancduced into a cellular response) without the signs, you don't have a cellular response
2) What structural element is absolutely required by a cell for it to respond to a signalling molecule?
- a receptor. without a receptor, the cell is blind to the signal
3) what is a protein kinase?
-enzyme that phosphorylates proteins
4) provide and example of a protein that is reversibly
-phosphorylated.P type pumps Na+ K+ ATP'ase
-When the receptor is active it will phosphorylate the protein, and it will later be de-phosphrylated by protein
Third type of receptors
in the case of g-protein receptors, they have seven transmembrane domains, (7TMD family) have a ligand
binding domain externally, on internally (cytosolic) they have a binding site for the G-protein, GTP, When the
receptor is active, it activates on the G-protein, which turns on the second mesenger. this molecule within
the cell carries on the message of the first cell.
G-proteins, are an example of a fatty acid membrane protein,
inserted to the cytosolic leaflet of the protein on the cytosolic side.
g-proteins are also heteroprimers. three different poly peptide chains
the g-proteins are able to bind Guanosine tri phosphate GTP, this allows g-protein to be active, and then it
separates into alpha and beta. when the GTP is hydrolyzed, this helps turn off the system.
GTP game S, can bind to protein, can since it cannot be hydrolyzed it cannot be turned off, and therefore it
-Most common pathways involves cyclic AMP (derivate of ATP)
to convert atp to cyclic AMP, two phosphates come off, and the remainning phosphate group is bridged in
between to carbons. You get cyclic cAMP from