ADD Cell signalling 2 Flashcards
Semester 1 year 1
What do receptor tyrosine kinases (RTK) do?
-pulls 2 subunits together once ligand binds
-brings together active site domains in the channel
-allow kinase proteins to cross phosphorylate tyrosine
-new charged receptor becomes docking site for other proteins
What do kinases do?
-phosphorylates amino acid residues (normally serine, tyrosine)
-changes the charge
What are RTK ligands and give an endocrine and paracrine example
-RTK ligands are peptide signals
-endocrine = insulin
-paracrine = growth factors
What do adapter proteins do?
-recognise + bind phosphorylated tyrosine residues
-activates intracellular pathways
Describe the cycle of the Ras GTPase switch
-GTP hydrolysed to GDP
-receptor/adapter activation causes Ras to bind to GTP - switched on
-Ras-GTP activates specific kinases which lead to cell proliferation
-Ras GTPase activity hydrolyses GTP to GDP - switched off
Describe the mechanism of G protein coupled receptors
-ligand binding activates a G protein
-causes it to bind to GTP + relay the signal
-activated G protein moves away from the receptor
-binds to effector enzyme, activating it
-effector enzyme produces second messenger
How is cyclic AMP produced?
-G protein coupled receptor activation can lead to adenylate cyclase activation
-adenylate cyclase produces cAMP
What does cAMP mainly activate?
Particular protein kinases
What are second messengers used for and what can they be produced by?
-they are often involved in generating responses within a cell
-can be produced by effectors associated with a receptor or coupled G-protein
What does receptor activation regulate?
-cellular metabolism
-transcription of specific genes in nucleus
-cell differentiation/division
-changes in cytoskeleton
Rank the 3 types of receptors in terms of their signalling speed
-ligand gated ion channels
-G protein coupled receptors
-receptor tyrosine kinases
