biostudies-literatureUng KLNovo Nordisk Fonden (Novo Nordisk Foundation)European Research CouncilDeutsche Forschungsgemeinschaft (German Research Foundation)Lundbeckfonden (Lundbeck Foundation)Danmarks Grundforskningsfond (Danish National Research Foundation)NIGMS NIH HHS1670-1680https://www.ebi.ac.uk/biostudies/studies/S-EPMC12364708biostudies-literatureUnknown11(8)Auxins are plant hormones that direct the growth and development of organisms on the basis of environmental cues. Indole-3-acetic acid (IAA) is the most abundant auxin in most plants. A variety of membrane transport proteins work together to distribute auxins. These include the AUX/LAX protein family that mediate auxin import from the apoplast to the cytosol. Here we use structural and biophysical approaches combined with molecular dynamics to study transport by Arabidopsis thaliana LAX3, which is essential for plant root formation. Transport assays document high-affinity transport of IAA, as well as competitive behaviour of the synthetic phenoxyacetic acid auxin herbicide 2,4-dichlorophenoxyacetic acid and the auxin transport inhibitors 1-naphthoxyacetic acid and 2-naphthoxyacetic acid. FNature plantsStructures and mechanism of the AUX/LAX transporters involved in auxin import.PMC12364708HA3468/8-1HA3468/6-3R35 GM144109R346-2020-1944NNF24OC0088380101000936190NF20OC0065431NNF18OC0032608NNF23OC0086406Schulz LAmsinck BLHammes UZZuzic LPedersen BPKoutnik-Abele SUng KLAndersen CGNel LSchiott BStokes DLBenhammouche IfalseStructures and mechanism of the AUX/LAX transporters involved in auxin import.Auxins are plant hormones that direct the growth and development of organisms on the basis of environmental cues. Indole-3-acetic acid (IAA) is the most abundant auxin in most plants. A variety of membrane transport proteins work together to distribute auxins. These include the AUX/LAX protein family that mediate auxin import from the apoplast to the cytosol. Here we use structural and biophysical approaches combined with molecular dynamics to study transport by Arabidopsis thaliana LAX3, which is essential for plant root formation. Transport assays document high-affinity transport of IAA, as well as competitive behaviour of the synthetic phenoxyacetic acid auxin herbicide 2,4-dichlorophenoxyacetic acid and the auxin transport inhibitors 1-naphthoxyacetic acid and 2-naphthoxyacetic acid. F2025-01-01T00:00:00Z2025 Aug2026-07-15T12:31:07.93Z2026-07-04T03:13:19.523ZS-EPMC123647084075976910.1038/s41477-025-02056-z