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<p>In vertebrates, newly synthesized lysosomal enzymes traffic to lysosomes through the mannose-6-phosphate (M6P) pathway. The Golgi membrane protein LYSET was recently discovered to regulate lysosome biogenesis by controlling the level of GlcNAc-1-phosphotransferase (GNPT). However, its working mechanism remained unclear. In this study, we demonstrate that LYSET is a two-transmembrane protein essential for GNPT stability, cleavage by Site-1 Protease (S1P), and enzymatic activity. We reconcile conflicting models by showing that LYSET enhances GNPT cleavage and prevents its mislocalization to lysosomes for degradation. We further establish that LYSET achieves this by interacting with GOLPH3 and retromer complexes to anchor the LYSET-GNPT complex at the Golgi. Alanine mutagenesis identified an F<sup>4</sup>XXR<sup>7</sup> motif in LYSET’s N-tail for GOLPH3 binding. The retromer further promotes Golgi retention by binding to the C-terminal of LYSET and recycling it from endolysosomes. Together, our findings reveal LYSET’s multifaceted role in stabilizing GNPT, retaining it at the Golgi, and ensuring the fidelity of the M6P pathway, thereby providing insights into its molecular function.</p>

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Molecular insights into the regulation of GNPTαβ by LYSET

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年3月11日

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  • Xi Yang,
  • Balraj Doray,
  • Danielle Henn,
  • Varsha Venkatarangan,
  • Benjamin C. Jennings,
  • Zhongzheng Dong,
  • Jiaxuan Liang,
  • Weichao Zhang,
  • Bokai Zhang,
  • Linchen Yu,
  • Liang Chen,
  • Stuart Kornfeld,
  • Ming Li

摘要

In vertebrates, newly synthesized lysosomal enzymes traffic to lysosomes through the mannose-6-phosphate (M6P) pathway. The Golgi membrane protein LYSET was recently discovered to regulate lysosome biogenesis by controlling the level of GlcNAc-1-phosphotransferase (GNPT). However, its working mechanism remained unclear. In this study, we demonstrate that LYSET is a two-transmembrane protein essential for GNPT stability, cleavage by Site-1 Protease (S1P), and enzymatic activity. We reconcile conflicting models by showing that LYSET enhances GNPT cleavage and prevents its mislocalization to lysosomes for degradation. We further establish that LYSET achieves this by interacting with GOLPH3 and retromer complexes to anchor the LYSET-GNPT complex at the Golgi. Alanine mutagenesis identified an F4XXR7 motif in LYSET’s N-tail for GOLPH3 binding. The retromer further promotes Golgi retention by binding to the C-terminal of LYSET and recycling it from endolysosomes. Together, our findings reveal LYSET’s multifaceted role in stabilizing GNPT, retaining it at the Golgi, and ensuring the fidelity of the M6P pathway, thereby providing insights into its molecular function.