Gβγ dually regulates the M-current via increased channel surface expression and PIP2 sensitivity

The M-current, generated by voltage gated K _V 7.2/7.3 channels, sets the threshold for neuronal action potential and acts as a key brake on repetitive firing. The M-current is tightly regulated by signaling molecules, such as calmodulin and phosphatidylinositol-4,5-bisphosphate (PIP ₂ ). Here, we show that coexpression of the ubiquitous subunit dimer of heterotrimeric G-proteins, Gβγ, with K _V 7.2/7.3 in Xenopus laevis oocytes doubles maximal M-current. This regulation requires free, prenylated, membrane–associated Gβγ and operates via two distinct mechanisms: 1) increasing plasma membrane (PM) channel density and 2) stabilizing K _V 7.2/7.3-PIP₂ coupling. Conversely, Gβγ scavengers reduce basal K _V 7.2/7.3 current and weaken PIP ₂ coupling. Proximity ligation assays confirm colocalization of Gβγ and K _V 7.2/7.3 in the PM. Peptide array and AlphaFold modeling identify putative interaction sites on the channel’s cytoplasmic domain. Finally, the disease–causing Gβ ₁ variant I80N abolished Gβγ–induced M-current potentiation. Together, these findings establish Gβγ as a significant physiological regulator and potential site of vulnerability in neuronal M-current function.