Related Experiment Video
Updated: May 13, 2026
08:55
Visualizing Intracellular SNARE Trafficking by Fluorescence Lifetime Imaging Microscopy
Published on: December 29, 2017
Syntaxin 17: the autophagosomal SNARE
Eisuke Itakura1, Noboru Mizushima
1MRC Laboratory of Molecular Biology, Cambridge, UK.
Autophagy
|March 8, 2013
Summary
Researchers identified syntaxin 17 (STX17) as a key protein regulating autophagosome-lysosome fusion. This discovery clarifies a crucial step in autophagy, the process cells use for waste removal and recycling.
Area of Science:
- Cell Biology
- Molecular Biology
- Autophagy Research
Background:
- Autophagosome formation involves the isolation membrane (phagophore) enclosing cytoplasm.
- Autophagosomes fuse with lysosomes for degradation, but the regulation of this fusion is unclear.
Purpose of the Study:
- To elucidate the molecular mechanism regulating autophagosome-lysosome fusion.
- To identify novel proteins involved in the fusion process.
Main Methods:
- Identification and characterization of syntaxin 17 (STX17) as an autophagosomal SNARE.
- Analysis of STX17's structure, localization, and interaction with other proteins (SNAP29, VAMP8).
Main Results:
- STX17 is specifically localized to completed autophagosomes, not phagophores, due to its unique transmembrane structure.
- STX17, SNAP29, and VAMP8 are essential for autophagosome-lysosome fusion.
- Late recruitment of STX17 prevents premature fusion with incomplete phagophores.
Conclusions:
- Syntaxin 17 (STX17) is a critical regulator of autophagosome-lysosome fusion.
- The specific localization and interactions of STX17 ensure efficient and timely autophagic degradation.
Related Concept Videos
01:43SNAREs and Membrane Fusion
Once a transport vesicle has recognized its target organelle, the vesicular membrane needs to fuse with the target membrane to unload the cargo. Transmembrane proteins called SNAREs present on organelle membranes and their vesicles, mediate vesicle fusion.
SNAREs exist in pairs that symmetrically interact and catalyze the fusion of the lipid bilayers in vesicle and target organelle. v-SNARE in the vesicle membrane are single polypeptide chains that bind to a complementary t-SNARE, composed of 2...
SNAREs exist in pairs that symmetrically interact and catalyze the fusion of the lipid bilayers in vesicle and target organelle. v-SNARE in the vesicle membrane are single polypeptide chains that bind to a complementary t-SNARE, composed of 2...
01:26Fusion of Secretory Vesicles with the Plasma Membrane
Proteins and neurotransmitters in secretory vesicles can be released from a cell upon vesicle docking, priming, and fusion with the plasma membrane. Vesicles are docked and primed in preparation for the quick exocytosis of their contents in response to a stimulus. The fusion process is mainly carried out by a SNAP Receptor or SNARE complex, consisting of synaptobrevin, syntaxin-1, and SNAP-25.
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...
01:28Protein Translocation Machinery on the ER Membrane
The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into the ER membrane.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
01:27Autophagy
Autophagy is a self-digesting process by which a cell protects itself from threats both within and outside the cell, ranging from abnormal proteins to invading bacteria. In this process, obsolete components of the cell and invading microbes are degraded by hydrolytic enzymes active in an acidic environment of the lysosomal lumen.
An autophagic pathway consists of a series of signaling events activated in response to diverse stress and physiological conditions such as food deprivation,...
An autophagic pathway consists of a series of signaling events activated in response to diverse stress and physiological conditions such as food deprivation,...
01:12Clathrin Coated Vesicles
Clathrin-coated vesicles use endocytosis to transport receptors and lysosomal hydrolases from the Golgi to the lysosome in the late secretory pathway. Clathrin-mediated endocytosis was the first described endocytic process, and Clathrin-coated vesicles remain one of the most well-studied transport vesicles. The molecular machinery that generates clathrin-coated vesicles comprises over 50 proteins that precisely coordinate vesicle formation. Cell surface receptors concentrated in indented sites...
01:38Intralumenal Vesicles and Multivesicular Bodies
Intraluminal vesicles (ILVs) are small vesicles 50-80 nm in diameter formed during the maturation of early endosomes. A specialized endosome containing numerous ILVs is called a multivesicular body (MVB). ILVs contain internalized molecules such as antigens, nucleic acids, proteins, and metabolites. Some of these molecules are released from the MVBs inside exosomes and are transported to other cells. Other MVBs contain molecules that are retained in the ILVs and are later degraded within the...