JPH203 inhibitor arrests LAT1 in the inwards-open conformation by displacing relevant water molecules | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article JPH203 inhibitor arrests LAT1 in the inwards-open conformation by displacing relevant water molecules Antti Poso, Jarkko Rautio, Kristiina Huttunen, Prasanthi Medarametla, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8019002/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract L-type amino acid transporter 1 (LAT1) delivers amino acids and aa-mimicking drugs across blood–brain barrier and is a key underexplored target against cancer. We investigated molecular triggers of LAT1 conformational changes upon ligand binding performing molecular dynamics simulations on LAT1-substrates and inhibitor. We realized LAT1 conformational change occurs via a two-step expansion/contraction of the mid-section and water flow propels substrate translocation. Expansion allows water flow from the extracellular H6/H10-pocket facilitating ligand flipping, while contraction promotes ligand movement toward H8 and water flow toward the intracellular region. Large substrates (cpd1) leave H6/H10 sub-pocket, toward H10–H3 and flipping mid-section for water flow, allowing H10 rotation and intracellular passage. Furthermore, benzoxazole tail of JPH203, a clinically investigated LAT1 inhibitor, can rotate downward during expansion phase, arresting LAT1 in the inward-open conformation by displacing unfavorable water molecules. This finding extends JPH203’s original mechanism, showing that it can block LAT1 not only in outward-facing conformation but by stabilizing the inward-open state. Biological sciences/Drug discovery/Medicinal chemistry/Computational chemistry Biological sciences/Chemical biology/Computational chemistry L-type amino acid transporter 1 (LAT1) Molecular dynamics (MD) simulations water transport JPH203 Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SI3.11.2025.docx Supporting Information - JPH203 arrests LAT1 in the inwards-open conformation by displacing relevant water molecules Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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