Characterization of a Druggable Binding site in the Renal Outer Medullary Potassium Channel

The Renal Outer Medullary potassium (K + ) channel, ROMK, has been postulated as a target for a novel class of loop diuretic. We recently used high‐throughput screening and medicinal chemistry to develop a highly selective small‐molecule inhibitor, termed VU591, with which to explore ROMK's physiology and therapeutic potential. Electrophysiological experiments suggested that VU591 blocks the intracellular pore of the channel. In an effort to characterize the VU591 binding site, a comparative homology model of ROMK based on the X‐ray structure of Kir2.2 was used to identify the pore‐lining residues to target for alanine‐scanning mutagenesis. Two‐electrode voltage clamp analysis of mutagenized channels expressed in Xenopus oocytes identified several pore‐lining residues that appear to be important for VU591‐dependent inhibition of ROMK. We are currently refining the mutagenesis and employing ligand‐docking simulations to help define molecular structure of the VU591 binding site. NIH R01 award to Jerod S. Denton DK082884.