TITLE:
Structural Requirements of RIN4 for Regulation of EXO70E2 Plasma Membrane Localization in Plant Cell
AUTHORS:
Kai Chen, Jianzhong Huang
KEYWORDS:
RIN4, EXO70E2, Exocyst, Subcellular Localization, Plasma Membrane, Protein Trafficking, Unconventional Secretion
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.17 No.9,
September
9,
2026
ABSTRACT: Protein localization is essential for maintaining cellular organization and function. EXO70E2, a plant-specific EXO70 family member, participates in exocyst-associated trafficking and unconventional secretion pathways. Our previous study demonstrated that RIN4 promotes EXO70E2 extracellular transport; however, the structural basis underlying this regulation remains unclear. Here, we investigated the structural requirements of RIN4-mediated EXO70E2 localization regulation using fluorescence localization analysis and RIN4 mutants. EXO70E2-YFP showed punctate intracellular localization when expressed alone, whereas co-expression with RIN4 promoted its redistribution toward the plasma membrane-associated region. The CCC/SSS mutation impaired RIN4-mediated EXO70E2 localization regulation, whereas T166 mutations showed limited effects. DTT-mediated perturbation further reduced EXO70E2 membrane accumulation. These findings indicate that the conserved cysteine cluster region and structural integrity of RIN4 contribute to EXO70E2 localization regulation, extending our understanding of RIN4-mediated control of plant trafficking-associated protein localization.