GPCRs/Calcium Flashcards
What is the normal extracellular Ca2+ concentration?
1x10-3 M (1mM)
What is the normal intracellular Ca2+ concentration?
1x10-7 M (100nm)
What is the normal SER/SR Ca2+ concentration?
2-3x10-4 M (200-300 micromoles)
What channels cause the influx of Ca2+ into the cytosol from the extracellular fluid? (4)
VOCC
Ligand Gated ion Channels
Store operated ion channels
NCX (when cell is heavily depolarised)
What channels cause the efflux of Ca2+ from the cytosol out of the cell?
NCX
PMCA
Which molecules are moved by the NCX? How many of each?
3Na+ into the cell
1Ca2+ out of the cell
What provides the concentration gradient for the movement of Na+ and Ca2+ at the NCX?
Concentration gradient set up by the Na/K ATPase pump
Which channels can result in the efflux of Ca2+ from SER/SR stores?
Ryanodine Receptors (RyRs) IP3 receptors
What type of GPCRs are activated to produce IP3 that can bind with IP3 receptors?
Galpha-q associated GPCRs
What acts as the ligand at RyRs? What is the process of efflux of Ca2+ at RyRs called?
Calcium ions
Calcium Induced Calcium Release
In which muscles is contraction driven by CICR?
Smooth muscle
Cardiac muscle
What is the main driver of Ca2+ release for contraction in skeletal muscle?
The T-tubule VOCCs are directly coupled with RyRs, so when VOCCs open, RyRs open
What proteins act to regulate Ca2+ cytosol concentrations and slows down diffusion of the ions within the cytoplasm?
Calcium ion buffer proteins
What is an example of a Ca2+ binding protein? Give an example of a protein it interacts with? How many calciums can it bind?
Calmodulin
Regulates activity of PMCA
Binds up to 4 calcium ions
What are the 3 superfamilies of cell surface receptor?
Kinase linked receptors (receptors with intrinsic enzymatic activity)
Ligand Gated ion Channels
G protein coupled receptors
Give an example of a ligand Gated ion channel. Give an example of a kinase linked receptor. Give an example of a GPCR.
Nicotinic ACh receptor
Insulin receptor
Muscarinic ACh receptor
What is affinity?
How well a ligand binds
What is efficacy?
How well a ligand causes a response
What is an agonist?
Molecule that binds to a receptor and activates it
What is an antagonist?
Molecule that binds to a receptor and does not activate it
Give two examples of B2-adrenoceptor agonists? Which disease are these drugs used in the treatment of?
Salbutamol
Salmeterol
Asthma
Give two examples of u-opioid receptor agonists? What are they used for?
Morphine, fentanyl
Analgesia/anaesthesia
Give two examples of b-adrenoceptor antagonists. What are they often used to treat?
Propranolol
Atenolol
Hypertension
Give two examples of d2-dopamine receptor antagonists. What are they used to treat?
Haloperidol
Sulpiride
Schizophrenia
GPCRs can respond to a small variety or great variety of stimuli?
A great variety of stimuli
GPCRs consist of how many polypeptide chains?
1