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bioRxiv · 10.64898/2026.04.10.716253

Auxin promotes GPI-anchored protein-mediated trafficking of ABP1 to enable cell-surface auxin signaling

Wang, J.·Ye, J.·Zhang, M.·Feng, H.·Liu, M.·Huang, Y.·Xu, T.·Lu, B.·Li, C.
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Abstract

Rapid auxin responses are triggered by Auxin-Binding Protein 1 (ABP1) signaling; however, the coupling of hormone perception to signaling activation is unclear. ABP1, a cell surface auxin receptor, is localized to endoplasmic reticulum (ER), raising a fundamental question of where auxin is perceived and how signaling-competent receptors are mobilized to cell surface. Herein, we established a dark-induced auxin synthesis system in Arabidopsis hypocotyl; abp1 mutants showed pronounced elongation. Auxin dose-dependently stimulates LORELEI-like glycosyl-phosphatidylinositol-anchored protein 1 (GPI-AP, LLG1) interaction with ABP1, driving their outward trafficking from ER. However, this complex dissociated in acidic apoplast, facilitating H+-ATPase-mediated auxin signaling. Our findings reveal how intracellular auxin perception is converted into rapid cell-surface signaling, establishing a mechanistic framework for fast auxin responses and uncovering a GPI-AP-mediated trafficking mechanism for ER-retained receptors.

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Wang, J., Ye, J., Zhang, M., Feng, H., Liu, M., Huang, Y., Xu, T., Lu, B., Li, C.. 2026-04-13. Auxin promotes GPI-anchored protein-mediated trafficking of ABP1 to enable cell-surface auxin signaling. https://doi.org/10.64898/2026.04.10.716253

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