This document contains all the information needed for the cell signalling sections of the BHCS2004 module at University of Plymouth. This module is run by Simon Fox. All information in this document is obtained from the lecture notes and external reading.
Cell Signalling Cheat Sheet
3 Main Classes of Ionotropic Receptors
Ligand Receptor Ion Response
Glutamate NMDA Na+ Fast depolarisation
Glutamate KA Na+ Fast depolarisation
Glutamate AMPA Na+ and Slow depolarisation and
Ca+ activation of second
messengers
NMDA
Magnesium blocks signalling and glycine modulates channel current
Channel gating may be blocked by agonists like ketamine
May be excitatory or inhibitory
2nd messenger activated downstream signalling pathways and post
translational modification by effectors
Calcium activates calmodium which activates effector proteins
Calcium
Activates post translational signalling pathways
This pathway causes phosphorylation of membrane channels
Channel gating may also result in prolonged changes like
transcriptional mediated changes
G- Protein Coupled Receptors
1. Cell produces signal
2. Binds to GCPR
3. G-protein (Guanine Nucleotide Binding Protein) produces 2nd
messenger
, 4. Activated target protein
5. Transcription, Survival, Protein synthesis
GTPase Regulation
When on - bound to GTP
When off - bound to GDP
G-protein Family
Composed of 3 subunits
Bring receptors to effectors which catalyses 2nd messenger
o Or bring receptors directly to ion channels
May be excitatory (N-epinephrine) or inhibitory (Ach)
Trimeric G-Proteins and GTP
1. G-protein inactivate - bound to GDP
2. Recruitment of 7TM - Gains GTP and loses GDP
3. Splits subunits
4. Hydrolyses GTP to GDP - terminating its own activity
G-proteins Couple to 3 Pathways
Direct effector linked pathway
Phospholipase C pathway
Adenyl Cyclase pathway
, Direct Effector Linked Pathway
Gby subunits directly to effector
Parasympathetic
1. Ach binds to heart muscle
2. Muscanic Ach receptor
3. G-protein
4. Opens K+
5. Hyperpolarisation
6. Decreased contraction
Motor Neuron
1. Ach binds to skeletal muscle
2. Nicotinic Ach receptor
3. Ion channel
4. Sodium and calcium flux
5. Depolarisation
6. Increased contraction
Adenyl Cyclase Pathway
Adenyl Cyclase is an enzyme that catalyses cAMP from ATP
Pathway
1. Norepinephrine
2. Beta adrenergic
3. G-protein
4. Adenyl Cyclase
5. cAMP
6. Protein kinase A
7. Increased phosphorylation of proteins
8. Increased cardiac contraction
Phospholipase C Pathway
Phospholipase C is an effector enzyme activated by G-protein
Pathway
1. Glu
2. mGlu
3. G-protein
4. Phospholipase C
5. Diacyldglycerol or IP3
6. Protein kinase C or Ca2+ release
7. Increased protein phosphorylation and calcium binding
proteins
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