GO:0030897 HOPS complex: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0030897 (HOPS complex) is a multimeric tethering complex that associates with vacuolar, late endosomal (multivesicular body) and lysosomal membranes and is required for vesicle fusion.
• The HOPS complex is composed of six subunits (Vps11, Vps16, Vps18, Vps33, Vps39 and Vps41) and is conserved from yeast to humans.
• HOPS functions as a tether that bridges opposing membranes and coordinates SNARE complex assembly to drive lysosomal and vacuolar fusion.
• Loss of HOPS subunits disrupts early-to-late endosome transition, impairs endosomal recycling and causes accumulation of amphisomes.
• HOPS is required for autophagosome-lysosome fusion, signaling endosome identity and TORC1 activity, and ciliogenesis.
• Pathogens such as African swine fever virus can inhibit autolysosome formation by disrupting RAB7-HOPS-dependent SNARE assembly.
Description
The HOPS complex (homotypic fusion and vacuole protein sorting) is a conserved multimeric tethering complex that localizes to vacuolar, late endosomal (multivesicular body) and lysosomal membranes and is essential for vesicle fusion. It was originally identified in yeast as a factor required for homotypic vacuole fusion, and its core architecture and function have since been characterized in higher eukaryotes. The complex acts as a molecular bridge that brings opposing membranes into close proximity and coordinates the assembly of SNARE proteins to drive membrane fusion. Because HOPS sits at the crossroads of endosomal maturation, autophagy and lysosomal degradation, it is a central node for researchers studying membrane trafficking, organelle biogenesis and cellular homeostasis. Defects in HOPS subunits have been linked to impaired autophagic flux, altered endosomal signaling and ciliogenesis defects, making the complex relevant to a broad range of cell biological and disease-oriented questions. This article summarizes the authoritative GO definition, the subunit composition and assembly of the complex, its molecular mechanism, the genes involved, and the experimental models and methods used to study it.
HOPS complex At A Glance
| GO ID | GO:0030897 |
|---|---|
| GO term | HOPS complex |
| Ontology | cellular_component |
| Synonym | none |
| Definition | A multimeric protein complex that associates with the vacuolar membrane, late endosomal (multivesicular body) and lysosomal membranes. HOPS is a tethering complex involved in vesicle fusion. |
| Major function | Tethering of opposing membranes and coordination of SNARE-mediated fusion at the vacuole, late endosome and lysosome |
| Subunit composition | Six subunits: Vps11, Vps16, Vps18, Vps33, Vps39 and Vps41 |
| Conservation | Conserved from yeast to humans |
| Associated processes | Autophagosome-lysosome fusion, endosome maturation, endosomal recycling, TORC1 signaling, ciliogenesis |
What Is GO:0030897?
According to the Gene Ontology, GO:0030897 (HOPS complex) is a multimeric protein complex that associates with the vacuolar membrane, late endosomal (multivesicular body) and lysosomal membranes. HOPS is a tethering complex involved in vesicle fusion. In other words, it is a membrane-associated protein machine that physically links a transport vesicle or autophagosome to a target organelle membrane and promotes the fusion of the two lipid bilayers.
Why Is HOPS complex Important in Cell Biology?
The HOPS complex is important because it is the principal tethering machinery for fusion events at the lysosome and vacuole, and it therefore controls the terminal steps of autophagy, endosomal maturation and lysosomal degradation. Without HOPS, autophagosomes and endocytic cargo cannot be delivered efficiently to lysosomes, leading to the accumulation of amphisomes and impaired recycling. HOPS also maintains signaling endosome identity and TORC1 activity, linking membrane trafficking to nutrient sensing and cell growth. In addition, HOPS subunits such as VPS39 contribute to ciliogenesis through autophagy, connecting the complex to primary cilium biology. Because of these central roles, HOPS is a frequent focus of studies on neurodegeneration, cancer, infection and ciliopathies, and it is a tractable target for CRISPR-based functional genomics.
• HOPS is the main tethering complex for vacuolar, late endosomal and lysosomal membrane fusion.
• It is required for autophagosome-lysosome fusion and therefore for autophagic flux.
• Loss of HOPS disrupts early-to-late endosome transition and endosomal recycling.
• HOPS maintains signaling endosome identity and TORC1 activity.
• The complex coordinates SNARE assembly through a RAB7-dependent mechanism.
• Vps41 acts as a molecular ruler that sets the distance for HOPS-mediated membrane fusion.
• HOPS subunit VPS39 controls ciliogenesis through autophagy.
• Pathogens can target the RAB7-HOPS-SNARE axis to block autolysosome formation.
• HOPS dysfunction leads to accumulation of amphisomes, a hallmark of impaired degradation.
• The complex is conserved from yeast to humans, enabling cross-species mechanistic studies.
HOPS complex: Biological Process, Structure and Molecular Mechanism
What Happens During HOPS complex-mediated fusion?
In simple terms: HOPS acts like a molecular rope that pulls two membranes together so they can merge.
During membrane fusion, the HOPS complex is recruited to the target membrane, where it tethers an incoming vesicle or autophagosome and promotes SNARE complex assembly. The complex associates with vacuolar, late endosomal and lysosomal membranes and is required for the fusion of these organelles with transport intermediates. In autophagy, HOPS mediates autophagosome-lysosome fusion, a step that is essential for the degradation of autophagic cargo. Loss of HOPS function disrupts the early-to-late endosome transition, impairs endosomal recycling and causes accumulation of amphisomes, indicating a block in degradative fusion. HOPS also supports signaling endosome identity and TORC1 activity, linking fusion events to nutrient signaling.
Structure and Composition of the HOPS complex
In simple terms: HOPS is built from six different proteins that fit together like a molecular machine.
The HOPS complex is a multimeric assembly composed of six subunits: Vps11, Vps16, Vps18, Vps33, Vps39 and Vps41. Structural studies have revealed the overall architecture of the complex, showing how the subunits are arranged to form an elongated tether that can span the distance between two membranes. Vps33 is a SM (Sec1/Munc18-like) protein that interacts with SNARE proteins, while Vps39 and Vps41 are implicated in membrane binding and RAB7 interaction. The complex is conserved from yeast to humans, and its subunit composition is largely maintained across species. Vps41 has been proposed to function as a molecular ruler that determines the distance over which HOPS can tether membranes before fusion.
Molecular Mechanism of HOPS complex
In simple terms: HOPS grabs the membranes, positions them correctly, and helps the SNARE proteins zip together to fuse them.
At the molecular level, HOPS functions as a tethering factor that brings opposing membranes into close apposition and then coordinates SNARE complex assembly to drive fusion. The complex interacts with the small GTPase RAB7, and this interaction is required for HOPS-dependent SNARE assembly and autolysosome formation. Vps33, a SM protein subunit of HOPS, is thought to regulate SNARE folding and assembly, while Vps39 and Vps41 contribute to membrane and RAB7 binding. The hookup model of the HOPS complex in autophagosome-lysosome fusion proposes that HOPS physically links the autophagosome and lysosome membranes before SNARE-mediated fusion. Vps41 acts as a molecular ruler that sets the distance for HOPS tethering complex-mediated membrane fusion, ensuring that the membranes are held at the correct separation for SNARE zippering.
Regulation of HOPS complex activity
In simple terms: HOPS does not work alone; it is switched on and off by small signaling proteins and cellular conditions.
HOPS activity is regulated by the small GTPase RAB7, which recruits and activates the complex at the lysosomal membrane. The complex is also linked to TORC1 signaling, as HOPS is required to maintain signaling endosome identity and TORC1 activity. In addition, HOPS function is connected to autophagy, and its subunit VPS39 controls ciliogenesis through autophagy, indicating that the complex is integrated into broader cellular stress and degradation pathways. Pathogens can modulate HOPS activity; for example, the African swine fever virus I10L protein inhibits autolysosome formation by disrupting RAB7-HOPS complex-dependent SNARE complex assembly.
Key Genes Involved in GO:0030897 HOPS complex
The HOPS complex is built from six core subunits, each encoded by a distinct gene, and these genes are the primary targets for functional studies.
| Gene | Major Role | Research Relevance |
|---|---|---|
| VPS11 | Core HOPS subunit | Required for complex assembly and membrane tethering |
| VPS16 | Core HOPS subunit | Essential for HOPS stability and function |
| VPS18 | Core HOPS subunit | Scaffold for complex assembly |
| VPS33 | SM protein subunit | Regulates SNARE complex assembly |
| VPS39 | HOPS subunit, RAB7 effector | Controls ciliogenesis through autophagy |
| VPS41 | HOPS subunit, molecular ruler | Sets distance for membrane fusion |
| RAB7 | Small GTPase | Recruits and activates HOPS at lysosomes |
| SNARE proteins | Fusion machinery | Mediate membrane fusion downstream of HOPS |
| TORC1 | Nutrient signaling kinase | Maintained by HOPS-dependent signaling endosomes |
| ATG proteins | Autophagy machinery | Cooperate with HOPS in autophagosome-lysosome fusion |
| LAMP1 | Lysosomal marker | Used to assess HOPS-dependent fusion |
| EEA1 | Early endosome marker | Used to monitor endosome transition defects |
| LC3 | Autophagosome marker | Readout for autophagic flux and amphisome accumulation |
| I10L (ASFV) | Viral inhibitor | Disrupts RAB7-HOPS-SNARE assembly |
How Is HOPS complex Regulated?
HOPS complex activity is regulated by the small GTPase RAB7, which recruits the complex to lysosomal membranes and is required for HOPS-dependent SNARE assembly. The complex is also functionally linked to TORC1 signaling, as HOPS is required to maintain signaling endosome identity and TORC1 activity. In addition, HOPS function intersects with autophagy, and its subunit VPS39 controls ciliogenesis through autophagy, indicating that the complex is regulated by cellular degradation and stress pathways. Pathogens can modulate HOPS activity; the African swine fever virus I10L protein inhibits autolysosome formation by disrupting RAB7-HOPS complex-dependent SNARE complex assembly.
HOPS complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| VPS39 | Ciliogenesis defects / ciliopathies | VPS39 knockout cells with cilia staining |
| VPS41 | Impaired membrane fusion / autophagic flux | VPS41 knockout or point-mutant cells |
| VPS11 | Endosomal trafficking defects | VPS11 knockout cell lines |
| VPS16 | Lysosomal dysfunction | VPS16 knockout cell lines |
| VPS18 | Autophagy impairment | VPS18 knockout cell lines |
| VPS33 | SNARE assembly defects | VPS33 knockout or mutant cells |
| RAB7 | Endolysosomal trafficking disease | RAB7 knockout or dominant-negative cells |
HOPS complex and autophagy-related disorders
HOPS is required for autophagosome-lysosome fusion, and loss of HOPS function disrupts early-to-late endosome transition, impairs endosomal recycling and induces accumulation of amphisomes. These defects are relevant to neurodegenerative diseases and lysosomal storage disorders in which autophagic flux is impaired. Because HOPS is central to degradative trafficking, mutations or reduced expression of HOPS subunits could contribute to pathologies characterized by autophagic stress.
HOPS complex and ciliopathies
The HOPS subunit VPS39 controls ciliogenesis through autophagy, linking the complex to primary cilium formation. Defects in ciliogenesis are associated with a group of human disorders known as ciliopathies, and HOPS dysfunction could therefore contribute to ciliary phenotypes. This connection positions HOPS as a potential modifier of ciliary disease mechanisms.
HOPS complex and infectious disease
Pathogens can target the HOPS complex to evade degradation. The African swine fever virus I10L protein inhibits autolysosome formation by disrupting RAB7-HOPS complex-dependent SNARE complex assembly. This highlights HOPS as a host factor that can be manipulated by viruses and as a potential target for antiviral strategies.
From HOPS complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of a HOPS subunit block autophagosome-lysosome fusion? | Knockout cell lines for VPS11, VPS16, VPS18, VPS33, VPS39 or VPS41 |
| Does a point mutation in VPS41 alter its molecular ruler function? | Point-mutation knock-in of VPS41 |
| Does VPS39 control ciliogenesis through autophagy? | VPS39 knockout or overexpression cells with cilia readouts |
| Does HOPS maintain TORC1 signaling? | Knockout or knockdown of HOPS subunits with TORC1 activity assays |
| Does a viral protein disrupt RAB7-HOPS-SNARE assembly? | Expression of viral I10L in HOPS-competent cells |
| Can HOPS subunit tagging reveal localization dynamics? | Tagged knock-in of HOPS subunits for live imaging |
How to Study the HOPS complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Fluorescence microscopy | Localization of HOPS subunits and organelle markers | Assessing HOPS recruitment to lysosomes |
| Live-cell imaging | Dynamics of tethering and fusion | Visualizing Vps41-dependent fusion |
| Co-immunoprecipitation | Protein-protein interactions | Testing HOPS-RAB7-SNARE interactions |
| Mass spectrometry | Subunit composition and interactome | Defining the HOPS complex |
| Autophagic flux assay | LC3 turnover and amphisome accumulation | Measuring HOPS-dependent degradation |
| Endosomal trafficking assay | Early-to-late endosome transition and recycling | Characterizing HOPS loss-of-function |
| TORC1 activity assay | Phosphorylation of downstream targets | Linking HOPS to nutrient signaling |
| Ciliogenesis assay | Primary cilium formation | Testing VPS39 function |
Imaging-based methods
Fluorescence microscopy of tagged HOPS subunits and organelle markers is used to visualize the localization of the complex at vacuolar, late endosomal and lysosomal membranes. Live-cell imaging of tagged Vps41 or Vps39 can reveal the dynamics of tethering and fusion events. Electron microscopy and correlative light-electron microscopy can resolve membrane apposition and fusion intermediates.
Biochemical and proteomic methods
Affinity purification followed by mass spectrometry is used to define the subunit composition of the HOPS complex and its interacting partners. Structural studies, including cryo-electron microscopy, have provided insights into the architecture of the complex. Co-immunoprecipitation can test interactions between HOPS subunits, RAB7 and SNARE proteins.
Functional assays for autophagy and endosomal trafficking
Autophagic flux is assessed by monitoring LC3 lipidation and turnover, and by quantifying amphisome accumulation in HOPS-deficient cells. Endosomal recycling and early-to-late endosome transition can be measured using uptake assays and marker colocalization. TORC1 activity is monitored by phosphorylation of downstream targets in HOPS mutant cells.
Genetic and CRISPR-based methods
CRISPR-Cas9 knockout of HOPS subunit genes is used to test loss-of-function phenotypes in autophagy, endosomal trafficking and ciliogenesis. Point mutations can be introduced to dissect domain-specific functions, such as the molecular ruler activity of VPS41. Tagged knock-in of HOPS subunits enables localization and interaction studies in live cells.
How CRISPR Can Be Used to Study GO:0030897 HOPS complex
Knockout
CRISPR-Cas9 knockout of HOPS subunit genes such as VPS11, VPS16, VPS18, VPS33, VPS39 and VPS41 is used to abolish complex function and to study the consequences for autophagosome-lysosome fusion, endosomal trafficking and ciliogenesis. Knockout cells show disrupted early-to-late endosome transition, impaired recycling and accumulation of amphisomes.
Point Mutation
Point mutations can be introduced into HOPS subunit genes to dissect domain-specific functions. For example, mutations in VPS41 can test its proposed role as a molecular ruler in membrane fusion. Point mutations in RAB7-interacting regions can probe the RAB7-HOPS interface.
Knock-in
Knock-in of epitope tags or fluorescent proteins into endogenous HOPS subunit loci enables live-cell imaging and biochemical purification of the complex under native expression conditions. Tagged knock-in of VPS39 or VPS41 can be used to track complex localization and dynamics.
Overexpression
Overexpression of wild-type or mutant HOPS subunits can be used to test gain-of-function phenotypes, to rescue knockout cells, or to study dominant-negative effects on membrane fusion. Overexpression of viral proteins such as ASFV I10L can be used to model pathogen-mediated disruption of RAB7-HOPS-SNARE assembly.
How EDITGENE Supports HOPS complex Research
Researchers studying HOPS complex-related genes often need to determine whether a candidate gene is causally involved in membrane trafficking, autophagy or ciliogenesis, and CRISPR-based models provide a direct way to test these hypotheses in relevant cell types.
Contact EDITGENE today to design your custom CRISPR model for HOPS complex research.
Frequently Asked Questions About HOPS complex
What is the HOPS complex?
The HOPS complex (GO:0030897) is a multimeric tethering complex that associates with vacuolar, late endosomal and lysosomal membranes and is required for vesicle fusion.
What genes are involved in the HOPS complex?
The core HOPS subunits are encoded by VPS11, VPS16, VPS18, VPS33, VPS39 and VPS41, and the complex also interacts with RAB7 and SNARE proteins.
What is the function of GO:0030897?
GO:0030897 describes a multimeric protein complex that tethers membranes and promotes vesicle fusion at the vacuole, late endosome and lysosome.
How does the HOPS complex mediate membrane fusion?
HOPS tethers opposing membranes and coordinates SNARE complex assembly, a process that requires RAB7 and is regulated by subunits such as Vps33, Vps39 and Vps41.
What happens when the HOPS complex is lost?
Loss of HOPS disrupts early-to-late endosome transition, impairs endosomal recycling and induces accumulation of amphisomes, indicating a block in autophagosome-lysosome fusion.
Is the HOPS complex involved in autophagy?
Yes, HOPS is required for autophagosome-lysosome fusion, and its dysfunction leads to impaired autophagic flux.
What is the role of VPS39 in the HOPS complex?
VPS39 is a HOPS subunit that controls ciliogenesis through autophagy and contributes to complex function at lysosomal membranes.
What is the role of VPS41 in the HOPS complex?
VPS41 functions as a molecular ruler that sets the distance for HOPS tethering complex-mediated membrane fusion.
How is the HOPS complex regulated?
HOPS activity is regulated by RAB7, which recruits and activates the complex, and is linked to TORC1 signaling and autophagy pathways.
Can viruses target the HOPS complex?
Yes, the African swine fever virus I10L protein inhibits autolysosome formation by disrupting RAB7-HOPS complex-dependent SNARE complex assembly.
Conclusion
The HOPS complex (GO:0030897) is a conserved six-subunit tethering machine that drives membrane fusion at the vacuole, late endosome and lysosome. Its central role in autophagosome-lysosome fusion, endosomal trafficking, TORC1 signaling and ciliogenesis makes it a key node for studies of cellular homeostasis and disease. Loss-of-function and point-mutation studies have revealed that HOPS subunits such as VPS39 and VPS41 have specialized functions, including ciliogenesis control and molecular ruler activity. Pathogen-driven disruption of the RAB7-HOPS-SNARE axis further highlights the complex as a therapeutic and host-defense target. CRISPR-based knockout, point-mutation, knock-in and overexpression models, combined with imaging and proteomic methods, provide a robust toolkit for dissecting HOPS biology in health and disease.
References
- 1. Zhang S et al.. 2024. The hookup model of the HOPS complex in autophagosome-lysosome fusion.. Autophagy 20(3):714-715 PMID: 38083843
- 2. Shvarev D et al.. 2022. Structure of the HOPS tethering complex, a lysosomal membrane fusion machinery.. Elife 11 PMID: 36098503
- 3. Gao J et al.. 2022. The HOPS tethering complex is required to maintain signaling endosome identity and TORC1 activity.. J Cell Biol 221(5) PMID: 35404387
- 5. König C et al.. 2025. Vps41 functions as a molecular ruler for HOPS tethering complex-mediated membrane fusion.. J Cell Sci 138(8) PMID: 40159992
- 6. Iaconis D et al.. 2020. The HOPS complex subunit VPS39 controls ciliogenesis through autophagy.. Hum Mol Genet 29(6):1018-1029 PMID: 32077937
- 7. van der Beek J et al.. 2024. Loss of the HOPS complex disrupts early-to-late endosome transition, impairs endosomal recycling and induces accumulation of amphisomes.. Mol Biol Cell 35(3):ar40 PMID: 38198575
- 8. Chen M et al.. 2026. African swine fever virus I10L protein inhibits autolysosome formation by disrupting RAB7-HOPS complex-dependent SNARE complex assembly.. Autophagy 22(9):2216-2231 PMID: 42138513
