Human NHE1 binds full-length calcineurin with high affinity and inhibits substrate dephosphorylation
Year: 2026
Type: preprint
Abstract: ABSTRACT Calcineurin (Cn) interacts with the Na + /H + -exchanger NHE1 through its calcineurin-binding domain (NHE1-CnBD). How activation of full-length Cn influences this interaction and its functional consequences has remained unclear. Here, we quantified the interaction between full-length human Cn and NHE1-CnBD in distinct activation states using fluorescence anisotropy and quantitative size-exclusion chromatography. Ca 2+ /calmodulin activation increased Cn affinity for NHE1-CnBD from submicromolar to tens of nanomolar affinity and stabilized the complex. NHE1-CnBD outcompeted the immunosuppressive cyclosporin A/cyclophilin A complex for Cn binding and selectively inhibited dephosphorylation of a phosphopeptide substrate while enhancing hydrolysis of p -nitrophenyl phosphate. These findings identify NHE1 as a high-affinity, substrate-competitive Cn regulator that blocks substrate recognition rather than catalysis, providing a mechanistic framework for reciprocal regulation between Cn and NHE1.
Institutions: University of Freiburg, Albstadt-Sigmaringen University
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
Awards: G1514386576, G2431691126, G259924242, SFB 1453: Nephrogenetik (NephGen), EXC 2189: CIBSS Centre for Integrative Biological Signalling Studies, G561423854, AcceleRating the Translation of virtual twins towards a pErsonalised Management of fatty lIver patients, SFB 1381: Dynamische Organisation zellulärer Proteinmaschinerien: Von der Biogenese und modularen Assemblierung zur Funktion
OpenAlex ID: W7213073561