The tolbutamide site of SUR1 and a mechanism for its functional coupling to K ATP channel closure

Micromolar concentrations of tolbutamide will inhibit (SUR1/K IR 6.2) 4 channels in pancreatic β‐cells, but not (SUR2A/K IR 6.2) 4 channels in cardiomyocytes. Inhibition does not require Mg 2+ or nucleotides and is enhanced by intracellular nucleotides. Using chimeras between SUR1 and SUR2A, we s…