METHOD FOR TRANSPORTING POTASSIUM ION FROM FRONT SIDE TO BACK SIDE OF LIPID BILAYER MEMBRANE

摘要

Disclosed are: a method for transporting a potassium ion from the front side to the back side of a lipid bilayer membrane upon the reaction with a chemical substance; and a method for detecting or quantifying a chemical substance utilizing the transporting method. Specifically disclosed is a method for transporting a potassium ion from the front side to the back side of a lipid bilayer membrane, which comprises the following steps (a) and (b): (a) a step of introducing a first plasmid capable of expressing a chemical substance receptor, a second plasmid capable of expressing a modified potassium ion channel GIRK4 in which a serine residue located at position-143 has been substituted by a threonine residue, and a third plasmid capable of expressing G protein into a cell to cause the co-expression of the chemical substance receptor, the modified potassium ion channel GIRK4 and G protein on a lipid bilayer membrane that constitutes the surface of the cell; and (b) a step of supplying the chemical substance from the front side of the lipid bilayer membrane to cause the binding of a subunit of G protein released by the action of the chemical substance receptor to the modified potassium ion channel GIRK4, thereby transporting a potassium ion from the front side to the back side of the lipid bilayer membrane.