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Updated: Jul 11, 2025
11:05
Analysis of Endocytic Uptake and Retrograde Transport to the Trans-Golgi Network Using Functionalized Nanobodies in Cultured Cells
Published on: February 21, 2019
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Structural determinants specific for retromer protein sorting nexin 5 in regulating subcellular retrograde membrane
Qing Chen1, Meiheng Sun1, Xu Han1
1Jiangsu Key Laboratory of Xenotransplantation, and Department of Medical Genetics, Nanjing Medical University, Nanjing, Jiangsu 211166, China.
Journal of Biomedical Research
|November 15, 2023
Summary
Sorting nexin 5 (SNX5) and sorting nexin 6 (SNX6) have distinct roles in endosomal trafficking. Differences in their Phox domain structural elements dictate SNX5 and SNX6
Area of Science:
- Cell Biology
- Molecular Biology
- Neuroscience
Background:
- Endosomal trafficking of signaling proteins is crucial for cellular function.
- The retromer complex, including sorting nexin (SNX) proteins, mediates this process.
- SNX5 and SNX6 isoforms exhibit distinct roles in retrograde membrane trafficking, but molecular mechanisms remain unclear.
Purpose of the Study:
- To elucidate the molecular basis for functional differences between SNX5 and SNX6 in retrograde trafficking.
- To investigate the interaction of SNX5 and SNX6 with the vesicular monoamine transporter 2 (VMAT2).
Main Methods:
- Analysis of binding affinity between SNX5, SNX6, and VMAT2.
- Site-directed mutagenesis and chimeric protein construction within the Phox domain.
- Functional rescue experiments assessing VMAT2 retrograde trafficking upon SNX5 depletion.
Main Results:
- SNX5, but not SNX6, specifically binds VMAT2 via its Phox domain.
- Key residues within the SNX5 Phox domain are critical for VMAT2 interaction.
- Mutating SNX6 to mimic SNX5 residues enhances VMAT2 binding and rescues VMAT2 trafficking defects.
Conclusions:
- Distinct structural elements within the Phox domain determine the differential functions of SNX5 and SNX6.
- SNX5 and SNX6 play unique roles in regulating VMAT2 retrograde trafficking.
- Findings offer insights into molecular mechanisms of vesicular targeting in neurotransmission and neurological disorders.
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