Acetylcholine and ACh R Flashcards
How many different type of acetylcholine receptors are there, and are they metabotropic or ionotropic?
2 types: nicotinic AChR (ionotropic, app. 32), and muscarinic AChR (metabotropic)
What are the agonists and antagonists of the acetylcholine Rs?
nAChR: agonists are ACh and nicotine, antagonists are curare and alfa-bungarotoxin
mAChR: agonists are ACh and muscarine, antagonist are atropine
Where does nAChR occur?
On skeletal muscles, para- and sympathetic ganglia and in the brain.
Describe the topology of the nAChR.
Pentameric consisting of different subunits (if oligomeric) alfa, beta, gamma/epsilon and delta. Each monomer: 4 TMs, M2 is part of the pore. The C- and N-terminus are extracellular. The binding site is between the alfa subunit and one of the other subunits. The principle binding site being on the alpha, while the complementary binding site is on the other.
What are the function of sarin and tabun?
They are warefare gasses, that block the acetylcholineaterase, causing overstimulation, and can result in heart stop.
How can a doctor treat sarin/tabun toxification?
Give the patient atropine, as it is an antagonist of the mAChRs.
Describe the cycle of ACh.
ACh is released from the pre-synaptic neuron and binds to AChR. The signal is stopped, and ACh is cleaved into acetat and choline by acetylcholinesterase on the post-synaptic membrane. Choline is re-uptaken by the pre-synaptic cell by a choline carrier (SLC5). AcetylCoA and choline is converted into acetylcholine by cholineacetyltransferase. Lastly the acetycholine is transported into synaptic vesicles (SLC18).
