| Summary: | 碩士 === 國立臺灣大學 === 生化科學研究所 === 105 === Autophagy is a self-digestive process that is important in balancing sources of energy at critical times during development and in response to nutrient stress. Upon autophagy induction, cytoplasmic constituents are engulfed within double-membraned vesicles known as an autophagosomes which eventually fuse with lysosomes and the contents are degraded and recycled. Although syntaxin17 (STX17), an autophagic SNARE, plays a vital role in autophagy induction and autophagosome maturation, little is known about whether tyrosine phosphorylation is implicated in the function of STX17.
Our recent data showed that Stx17 is tyrosine phosphorylated under starvation. There are three conserved tyrosine residues in STX17, mutational analysis showed one tyrosine residue in the cytoplasmic domain of STX17 as the major site of phosphorylation. We further found that tyrosine mutation of STX17 results in autophagic defects. TC48 and PTP1B were identified as the phosphatase of STX17, moreover, Src was identified as the kinase of STX17. We were curious about the mechanism of phosphorylation of STX17 in the autophagy. Our data suggested that STX17 mutants regulate SNARE complex assembly.
Taken together, we propose that Src phosphorylates Syntaxin17. Furthermore, the dephosphorylation of Syntaxin17 during starvation requires TC48 and PTP1B. In addition, we suggest that tyrosine phosphorylation of Syntaxin 17 is likely to have a role in regulating the assembly of the SNARE complex.
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