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37 Cards in this Set

  • Front
  • Back
What are the 3 types of membrane receptors?
1. Ion channel linked (ionotropic)
2. GPCR (metabotropic)
3. Enzyme-linked
What are 4 important characteristics of Ion channel-linked receptors?
1. It is a common gene family
2. The receptor directly gates an ion channel
3. These are major drug targets
4. Allows for RAPID signalling
What are the 2 major ionotropic receptors?
-Nicotinic ACh receptors
-GABA receptor gated Cl channels
What is GABA?
Gamma-aminobutyric acid
What is the nicotinic ACh receptor a channel for?
Pos cations - Na/K
What is the response of the cell when ACh binds to the nicotinic cholinergic ionotropic receptor?
Excitation - Depolarization
At what 3 sites is the nicotinic ACh receptor located?
-Autonomic PNS
What is the GABA receptor an ion channel for?
What is the cell response when GABA binds its receptor?
Hyperpolerization so Inhibition
Where is GABA found operating on these GABA receptors?
What is GABA then?
The main post synaptic inhibitory neurotransmitter in the CNS
What are 2 drugs that act via increasing the sensitivity of the GABA receptor? How do they work?
-Allow lower concentrations of GABA to open the channel
What is the main general feature of the GPCR?
It is a multi component system!
How many GPCRs are there in the large family of them?
What are 5 effects mediated by GPCRs?
-Other extracellular messengers like growth factors and cytokines
What makes up the receptor component of GPCRs?
A single 7-transmembrane protein
To what is the 7-TM protein coupled?
Heterotrimeric G proteins
What is a heterotrimeric G protein?
A Guanine nucleotide binding protein that links the ligand-activated GPCR to effector enzymes
So for the GPCR complex
-What provides specificity?
-What does the transducing?
-What is the effector?
Specificity = 7TM receptor
Transducer = G-protein
Effector = the catalytic component that generates a 2nd messenger
How do Heterotrimeric G-proteins exist?
As molecular switches that cycle between two states
What are the 2 states that G-proteins cycle between?
Active - GTP bound
Inactive - GDP bound
What do Heterotrimeric G proteins consist of?
3 proteins (subunits)
What are the 3 subunits that G proteins are composed of?
-G alpha
-G beta
-G gamma
What is the function of Ga?
Binds GTP/GDP, functions as a GTPase
What is the function of GB-Gy?
-Membrane anchor
How are heterotrimeric G proteins classified?
According to the type of G-a that is present in the trimer
What does Ga-s do?
Stimulates adenylate cyclase which activates PKA
What does Ga-i do?
Inhibits adenylate cyclase which inactivates PKA
What does Gaq do?
Activates phospholipase C which turns on PKC
What is the general feature to know about Enzyme-linked receptors?
They are a diverse group of receptors with different enzymatic activities.
What is the most important enzyme-linked receptor?
Tyrosine Kinase linked Receptors
What happens when ligand binds to a TKLR?
What follows dimerization of a TKLR?
Acivation by crossphosphorylation (auto) of the internal domains
What follows autophorphorylation of the cytoplasmic domains?
Intracellular signaling molecules bind
What gets regulated by the intracellular signalling molecules?
Cell proliferation and differentiation
What 3 ligand types utilize TKLRs to regulate cell proliferation and differentiation?
-Growth factors
What disease process do TKLRs play an important role in?