Kir6.2△C26 Channel Traffics to Plasma Membrane by Constitutive Exocytosis

摘要

Adenosine triphosphate (ATP)-sensitive K+ (KATP) channels regulate many cellular functions by coupling the metabolic state of the cell to the changes in membrane potential. Truncation of C-terminal 26 amino acid residues of Kir6.2 protein (Kir6.2△C26) deletes its endoplasmic reticulum retention signal, allowing functional expression of Kir6.2 in the absence of sulfonylurea receptor subunit. pEGFP-Kir6.2△C26 and pKir6.2△C26-IRES2-EGFP expression plasmids were constructed and transfected into HEK293 cells. We identified that Kir6.2△C26 was localized on the plasma membrane and trafficked to the plasmalemma by means of constitutive exocytosis of Kir6.2△C26 transport vesicles, using epi-fluorescence and total internal reflection fluorescence microscopy. Our electrophysiological data showed that Kir6.2△C26 alone expressed KATP currents, whereas EGFP-Kir6.2△C26 fusion protein displayed no KATP channel activity.