biostudies-literatureXu YFNational Science Fund for Distinguished Young ScholarsNational Key Basic Research Program of China GrantKey Research Project of the Natural Science Foundation of BeijingNational Natural Science Foundation of ChinaChina Postdoctoral Science FoundationNational Institutes of HealthNational Natural Science Foundation of China (NSFC)Fundamental Research Funds of Shandong UniversityShandong University Multidisciplinary Research and Innovation Team of Young ScholarsNational Science Fund for Excellent Young ScholarsAcademic promotion programme of Shandong First Medical UniversityHHS|National Institutes of Health (NIH)Shandong Provincial Natural Science FoundationCOVID-19 Emergency Tackling Research Program of Shandong UniversityNatural Science Foundation of Shandong Province (Natural Science Foundation of Shandong)Fundamental Research Fund of Shandong UniversityNatural Science Foundation of Shandong ProvinceSDU|Fundamental Research Fund of Shandong UniversityNCI NIH HHSNSFC|National Science Fund for Distinguished Young Scholars (National Science Foundation for Distinguished Young Scholars)e52141https://www.ebi.ac.uk/biostudies/studies/S-EPMC8097337biostudies-literatureUnknown22(5)Tyrosine phosphorylation of secretion machinery proteins is a crucial regulatory mechanism for exocytosis. However, the participation of protein tyrosine phosphatases (PTPs) in different exocytosis stages has not been defined. Here we demonstrate that PTP-MEG2 controls multiple steps of catecholamine secretion. Biochemical and crystallographic analyses reveal key residues that govern the interaction between PTP-MEG2 and its substrate, a peptide containing the phosphorylated NSF-pY⁸³ site, specify PTP-MEG2 substrate selectivity, and modulate the fusion of catecholamine-containing vesicles. Unexpectedly, delineation of PTP-MEG2 mutants along with the NSF binding interface reveals that PTP-MEG2 controls the fusion pore opening through NSF independent mechanisms. Utilizing bioinformatics search and biochemical and electrochemical screening approaches, we uncover that PTP-MEG2 regulates the opening and extension of the fusion pore by dephosphorylating the DYNAMIN2-pY¹²⁵ and MUNC18-1-pY¹⁴⁵ sites. Further structural and biochemical analyses confirmed the interaction of PTP-MEG2 with MUNC18-1-pY¹⁴⁵ or DYNAMIN2-pY¹²⁵ through a distinct structural basis compared with that of the NSF-pY⁸³ site. Our studies thus provide mechanistic insights in complex exocytosis processes.EMBO reportsPTP-MEG2 regulates quantal size and fusion pore opening through two distinct structural bases and substrates.PMC80973372017JQ022020QNQT0028182200882072676ZR2017BC045ZR2020ZD39R01 CA069202817737042018YFC10036002020M682190CA6920281825022317012302020XGB02817004732019QL009Z200019Liu CHCui MZhao WDWang CHWang CZhang ZYZhu ZLZhang SYang XZWang YJXiao PJi ZLYang ZLi KSSong YCChen XXu YFXu ZGYu XSun JPfalsePTP-MEG2 regulates quantal size and fusion pore opening through two distinct structural bases and substrates.Tyrosine phosphorylation of secretion machinery proteins is a crucial regulatory mechanism for exocytosis. However, the participation of protein tyrosine phosphatases (PTPs) in different exocytosis stages has not been defined. Here we demonstrate that PTP-MEG2 controls multiple steps of catecholamine secretion. Biochemical and crystallographic analyses reveal key residues that govern the interaction between PTP-MEG2 and its substrate, a peptide containing the phosphorylated NSF-pY⁸³ site, specify PTP-MEG2 substrate selectivity, and modulate the fusion of catecholamine-containing vesicles. Unexpectedly, delineation of PTP-MEG2 mutants along with the NSF binding interface reveals that PTP-MEG2 controls the fusion pore opening through NSF independent mechanisms. Utilizing bioinformatics search and biochemical and electrochemical screening approaches, we uncover that PTP-MEG2 regulates the opening and extension of the fusion pore by dephosphorylating the DYNAMIN2-pY¹²⁵ and MUNC18-1-pY¹⁴⁵ sites. Further structural and biochemical analyses confirmed the interaction of PTP-MEG2 with MUNC18-1-pY¹⁴⁵ or DYNAMIN2-pY¹²⁵ through a distinct structural basis compared with that of the NSF-pY⁸³ site. Our studies thus provide mechanistic insights in complex exocytosis processes.2021-01-01T00:00:00Z2021 May2026-05-31T09:47:51.424Z2025-02-18T23:32:21.618ZS-EPMC80973373376461810.15252/embr.202052141