9C0H

Phosphorylated human NKCC1 in complex with bumetanide

Summary for 9C0H

• Entry DOI: 10.2210/pdb9c0h/pdb
• EMDB information: 45084
• Descriptor: Solute carrier family 12 member 2, POTASSIUM ION, CHLORIDE ION, ... (5 entities in total)
• Functional Keywords: phosphorylation, sodium potassium chloride cotransporter, outward-open, bumetanide, transport protein
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 2
• Total formula weight: 264410.70

Authors

Zhao, Y.X.,Cao, E.H. (deposition date: 2024-05-25, release date: 2025-02-12, Last modification date: 2025-05-14)

Primary citation

Zhao, Y.,Vidossich, P.,Forbush, B.,Ma, J.,Rinehart, J.,De Vivo, M.,Cao, E.
Structural basis for human NKCC1 inhibition by loop diuretic drugs.
Embo J., 44:1540-1562, 2025

PubMed Abstract: Na-K-Cl cotransporters functions as an anion importers, regulating trans-epithelial chloride secretion, cell volume, and renal salt reabsorption. Loop diuretics, including furosemide, bumetanide, and torsemide, antagonize both NKCC1 and NKCC2, and are first-line medicines for the treatment of edema and hypertension. NKCC1 activation by the molecular crowding sensing WNK kinases is critical if cells are to combat shrinkage during hypertonic stress; however, how phosphorylation accelerates NKCC1 ion transport remains unclear. Here, we present co-structures of phospho-activated NKCC1 bound with furosemide, bumetanide, or torsemide showing that furosemide and bumetanide utilize a carboxyl group to coordinate and co-occlude a K, whereas torsemide encroaches and expels the K from the site. We also found that an amino-terminal segment of NKCC1, once phosphorylated, interacts with the carboxyl-terminal domain, and together, they engage with intracellular ion exit and appear to be poised to facilitate rapid ion translocation. Together, these findings enhance our understanding of NKCC-mediated epithelial ion transport and the molecular mechanisms of its inhibition by loop diuretics.

PubMed: 39875725
DOI: 10.1038/s44318-025-00368-6

Experimental method

ELECTRON MICROSCOPY (2.5 Å)