molecular and cellular biology 08.1. cell signalling i: signal transduction and...
TRANSCRIPT
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Molecular and Cellular Biology
08.1. Cell Signalling I:
Signal Transduction and Short-Term
Cellular Responses
Prof. Dr. Klaus Heese
- G-protein signalling
Cell – Cell Communication Cell – Cell CommunicationNeuron-Neuron
or Neuron-Muscle
Synaptic Transmission
Neurotransmitters in the brain
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Ligand – Receptor interactionexperimental
Cell signalling
studies
e.g. pharmaceutical industry studies
G-Protein
Signalling
GTP/GDP
On / Off switch
Second Messengers in Cell Signalling
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G-Protein-Coupled Receptor - 7-TransMembrane-Receptors
a 7TM-GPCR
G-protein-
coupled Receptor
7-TM-Rs
Hormone /G-Protein-Coupled Receptor Signalling Ligand
In-Vitro Fluorescence-activated live-Cell Imaging Analysis of G-Protein-Coupled Receptor Signalling
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Ligand
ligand
7TM-GPCR
G-protein
Effector
2nd messenger
activated target(change in membrane potential and ion-gradient)
Rhodopsin
Signalling
in a human
Rod Cell
(eye/vision)
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(conformation change)
Rhodopsin consists of the protein moiety
opsin and a reversibly
covalently bound cofactor, retinal.
PDE:cGMP PhosphoDiEsterase
ligand
7TM-GPCR(Rhodopsin =(opsin+retinal)
G-protein
Effector
2nd messenger
activated target:Ion channel
---> 3rd messenger --->(change in membrane potential and ion-gradients)
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effector protein/enzyme
(secondmessenger)
Different Ligand/Receptor systems may modulate/act on the same Effector
activated target: e.g. PKA
effector-
protein/enzyme
Signalling
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cAMP-PKA Signalling
& Cell Metabolism
Signal Amplification
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cAMP-PKA-PDE control cycle
GPCR – Ca2+ Signalling GPCR – Ca2+ Signalling
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Example
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2nd messenger