Question

You are studying a cell that contains ACh-activated GIRK channels. Which of the following dimers would increase the ability of the cell to fire action potentials in the presence of ACh, and why?

a. β-γ dimer, becasue this dimer decreases the amount of open GIRK channels in the cell and therefore reduces their hyperpolarizing effect on the cell, increasing its ability to fire an action potential.

b. α-GDP dimer, because this dimer would bind to the β-γ dimer leading to a decrease in the amount of open GIRK channels in the cell and, therefore, a reduction in the GIRK channels’ hyperpolarizing effect on the cell, increasing the cell’s ability to fire an action potential.

c. β-γ dimer, becasue this dimer increases the amount of open GIRK channels in the cell which would then increase the ability of the cell to fire action potentials.

d. α-GTP dimer, because this dimer would bind to the β-γ dimer leading to a decrease in the amount of open GIRK channels in the cell and, therefore, a reduction in the GIRK channels’ hyperpolarizing effect on the cell, increasing the cell’s ability to fire an action potential.

Answer 1

c. β-γ dimer, because this dimer increases the number of open GIRK channels in the cell which would then increase the ability of the cell to fire action potentials.

actually β-γ dimer interacts with the GIRKs channel and opens it. this dimer break from the trimer in G protein-coupled receptor where α-β-γ is found in their inactive forms. it is activated by the GTP

. GTP bound to the α subunit of the α-β-γ trimer of G protein-coupled receptor and degrade into α-GTP and β-γ dimer and this dimer attaches to GIRK and boost to activate or open the K channel.

thanks alot