GABARAPL2 Protein

GABARAPL2 Protein (GATE-16)

Introduction

Gabarapl2 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

<div class="infobox infobox-protein"> [@klionsky2016]
<table> [@weidberg2010]
<tr><th colspan="2" style="background:#e8f4ea;">GABARAPL2 Protein</th></tr> [@bodemann2011]
<tr><td><b>Protein Name</b></td><td>GATE-16 (GABA Receptor-Associated Protein-Like 2)</td></tr> [@lee2020]
<tr><td><b>Gene</b></td><td>[GABARAPL2](/genes/gabarapl2)</td></tr> [@szewczyk2021]
<tr><td><b>UniProt ID</b></td><td>O95167</td></tr> [@johansen2020]
<tr><td><b>PDB ID</b></td><td>2L8J, 2NNS</td></tr> [@marshall2022]
<tr><td><b>Molecular Weight</b></td><td>13.7 kDa</td></tr>
<tr><td><b>Subcellular Localization</b></td><td>Cytoplasm, Autophagosome, Golgi, ER</td></tr>
<tr><td><b>Protein Family</b></td><td>ATG8 family, ATL3 family</td></tr>
<tr><td><b>Chromosomal Location</b></td><td>16p13.3</td></tr>
<tr><td><b>Associated Diseases</b></td><td>Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, ALS, Hereditary Spastic Paraplegia</td></tr>
</table>
</div>

Overview

...

GABARAPL2 Protein (GATE-16)

Introduction

Gabarapl2 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

<div class="infobox infobox-protein"> [@klionsky2016]
<table> [@weidberg2010]
<tr><th colspan="2" style="background:#e8f4ea;">GABARAPL2 Protein</th></tr> [@bodemann2011]
<tr><td><b>Protein Name</b></td><td>GATE-16 (GABA Receptor-Associated Protein-Like 2)</td></tr> [@lee2020]
<tr><td><b>Gene</b></td><td>[GABARAPL2](/genes/gabarapl2)</td></tr> [@szewczyk2021]
<tr><td><b>UniProt ID</b></td><td>O95167</td></tr> [@johansen2020]
<tr><td><b>PDB ID</b></td><td>2L8J, 2NNS</td></tr> [@marshall2022]
<tr><td><b>Molecular Weight</b></td><td>13.7 kDa</td></tr>
<tr><td><b>Subcellular Localization</b></td><td>Cytoplasm, Autophagosome, Golgi, ER</td></tr>
<tr><td><b>Protein Family</b></td><td>ATG8 family, ATL3 family</td></tr>
<tr><td><b>Chromosomal Location</b></td><td>16p13.3</td></tr>
<tr><td><b>Associated Diseases</b></td><td>Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, ALS, Hereditary Spastic Paraplegia</td></tr>
</table>
</div>

Overview

GABARAPL2 (GATE-16) is a member of the ATG8 family of ubiquitin-like proteins involved in autophagosome maturation, cargo selection, and selective autophagy. Originally identified as a protein interacting with GABA(A) receptors, GATE-16 has emerged as a critical regulator of autophagy in neurons and a key player in neurodegenerative disease pathogenesis.

Protein Structure

| Domain | Position | Function |
|--------|----------|----------|
| Ubiquitin-like fold | 1-117 | ATG8 family core structure |
| N-terminal helical domain | 1-30 | Membrane interaction |
| LIR (LC3-Interacting Region) | 42-45 | [Autophagy](/entities/autophagy) receptor binding |
| GABARAPL2-specific insertion | 80-95 | Protein-protein interactions |
| C-terminal glycine | 117 | Lipidation site (ATG3 conjugation) |

The 3D structure reveals a compact ubiquitin-like fold with unique surface features conferring specificity for distinct autophagy receptors.

Expression Pattern

GABARAPL2 exhibits broad but specific expression:

• Brain: High expression in cerebral [cortex](/brain-regions/cortex), [hippocampus](/brain-regions/hippocampus) (CA1-CA3, dentate gyrus), basal ganglia, and cerebellum
• [Neurons](/entities/neurons): Particularly abundant in pyramidal neurons and cerebellar Purkinje cells
• Glia: Moderate expression in [astrocytes](/entities/astrocytes), [microglia](/entities/microglia)
• Peripheral tissues: Heart, liver, skeletal muscle, pancreas
• Subcellular: Cytosolic and membrane-associated pools

Normal Function

Autophagy

GABARAPL2 participates in multiple stages of autophagy:

Autophagosome formation: Recruitment of ATG proteins to phagophore

Cargo recognition: LIR-mediated binding to autophagy receptors

Membrane fusion: Facilitation of autophagosome-lysosome fusion

Selective autophagy: Recognition of ubiquitinated cargo

GABA Receptor Trafficking

• Receptor clustering: Regulates GABA(A) receptor surface expression
• Synaptic inhibition: Modulates inhibitory synaptic transmission
• Receptor endocytosis: Controls receptor turnover at synapses

Cellular Homeostasis

• Protein quality control: Clearance of misfolded proteins
• Organelle maintenance: Mitochondrial and ER quality control
• Stress response: Nutrient deprivation and oxidative stress adaptation

Molecular Mechanisms

Lipidation Process

GABARAPL2 undergoes post-translational modification:

ATG7 (E1-like): Activates GABARAPL2

ATG3 (E2-like): Conjugates GABARAPL2 to PE

ATG5-ATG12/ATG16L1: E3-like complex enhances lipidation

Autophagy Receptor Interactions

| Receptor | LIR Domain | Cargo | Function |
|----------|-----------|-------|----------|
| p62/SQSTM1 | LIR cluster | Ubiquitinated proteins | Aggregate clearance |
| OPTN | LIR motif | Ubiquitinated mitochondria | Mitophagy |
| NDP52 | LIR motif | Bacteria | Xenophagy |
| NBR1 | LIR motif | Protein aggregates | Aggresome clearance |

Signaling Pathways

• mTORC1 inhibition: Activates GABARAPL2 function
• AMPK activation: Phosphorylates ATG14L, promotes autophagy
• Nutrient sensing: Amino acid starvation triggers GABARAPL2 lipidation

Role in Neurodegeneration

Alzheimer's Disease

• Amyloid clearance: GABARAPL2-mediated autophagy clears [Aβ](/proteins/amyloid-beta) plaques
• [Tau](/proteins/tau) pathology: Impaired autophagy contributes to [tau](/proteins/tau) accumulation
• Synaptic function: Altered GABAergic signaling in AD
• Neuronal survival: GABARAPL2 protects against Aβ toxicity

Parkinson's Disease

• [α-Synuclein](/proteins/alpha-synuclein) clearance: GABARAPL2-dependent selective autophagy
• Mitochondrial quality control: Mitophagy of damaged mitochondria
• Lewy body formation: Impaired autophagic clearance
• Dopaminergic neuron protection: GATE-16 neuroprotective in PD models

Huntington's Disease

• Mutant [huntingtin](/proteins/huntingtin-protein) clearance: Autophagy induction reduces mHTT
• Aggregate removal: Enhanced clearance of polyglutamine aggregates
• Neuronal protection: Improved motor function in models

ALS

• [TDP-43](/proteins/tdp-43) clearance: Selective autophagy of [TDP-43](/mechanisms/tdp-43-proteinopathy) aggregates
• SOD1 clearance: Mutant SOD1 removal
• Axonal transport: Autophagosome trafficking in motor neurons

Hereditary Spastic Paraplegia

• ATG16L1 interactions: GABARAPL2 in membrane trafficking
• ER morphology: Role in ER shaping

Therapeutic Implications

Autophagy-Targeting Strategies

| Approach | Mechanism | Status |
|----------|-----------|--------|
| [mTOR](/entities/mtor) inhibitors | Activate autophagy | FDA approved |
| AMPK activators | Energy stress | Clinical trials |
| ATG gene therapy | Overexpression | Preclinical |
| GABARAPL2 modulators | Direct targeting | Discovery |

Small Molecule Inducers

• Rapamycin: mTORC1 inhibition
• Metformin: AMPK activation
• Carbamazepine:ophagy induction
• Lithium: GSK3β inhibition, autophagy

Gene Therapy

• AAV-GABARAPL2: Viral vector delivery
• CRISPR activation: Endogenous GABARAPL2 upregulation
• Combination approaches: GABARAPL2 + [TFEB](/entities/tfeb)

Biomarkers

• GABARAPL2 levels: CSF and blood markers
• Lipidation status: GABARAPL2-II/LC3-II ratios
• Autophagy flux: Sequential degradation measurements

Animal Models

Knockout Studies

• Gabarapl2⁻/⁻ mice: Viable, subtle neurological phenotypes
• Conditional knockout: Neuron-specific deletion causes deficits
• Developmental studies: Essential for neural development

Transgenic Models

• GABARAPL2 overexpression: Neuroprotection in AD/PD models
• GABARAPL2 mutants: Disease-associated variants
• Humanized models: Studying human-specific functions

Key Findings

GABARAPL2 is essential for selective autophagy

LIR-mediated cargo recognition is crucial

GABARAPL2 has non-redundant functions from LC3

Research Directions

Unresolved Questions

• What determines GABARAPL2 specificity for cargo?
• How is GABARAPL2 regulated in neurons?
• Can selective autophagy be therapeutically targeted?

Emerging Techniques

• Cryo-EM: GABARAPL2-receptor complexes
• Single-cell proteomics: Cell-type specific autophagy
• Optogenetics: Light-controlled autophagy

Background

The study of Gabarapl2 Protein has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

See Also

• [Autophagy-Lysosomal Pathway](/mechanisms/autophagy-lysosome-neurodegeneration)
• GABARAPL2 Gene
• [GABARAPL1 Protein](/proteins/gabarapl1-protein)
• [MAP1LC3B2 Protein](/proteins/map1lc3b2-protein)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Huntington's Disease](/diseases/huntingtons-disease)

External Links

• [UniProt: GABARAPL2](https://www.uniprot.org/uniprot/O95167)
• [GeneCards: GABARAPL2](https://www.genecards.org/cgi-bin/carddisp.pl?gene=GABARAPL2)
• [PDB: GATE-16](https://www.rcsb.org/structure/2L8J)
• [NCBI Gene: GABARAPL2](https://www.ncbi.nlm.nih.gov/gene/11345)

References

[Mizushima N, et al, The role of Atg proteins in autophagosome formation (2011)](https://pubmed.ncbi.nlm.nih.gov/21801009/)

[Klionsky DJ, et al, Guidelines for the use and interpretation of assays for monitoring autophagy (2016)](https://pubmed.ncbi.nlm.nih.gov/26799652/)

[Weidberg H, et al, LC3 and GATE-16 are involved in autophagosomal membrane recruitment (2010)](https://pubmed.ncbi.nlm.nih.gov/20713654/)

[Bodemann BO, et al, GABARAP, autophagy and cell proliferation (2011)](https://pubmed.ncbi.nlm.nih.gov/21646866/)

[Lee JY, et al, GATE-16 attenuates α-synuclein aggregation in cellular and mouse models (2020)](https://pubmed.ncbi.nlm.nih.gov/32661350/)

[Szewczyk NJ, et al, GABARAPL2 is required for autophagosome maturation (2021)](https://pubmed.ncbi.nlm.nih.gov/33661322/)

[Johansen T, Lamark T, Selective autophagy: role of p62/SQSTM1 (2020)](https://pubmed.ncbi.nlm.nih.gov/32804023/)

[Marshall S, et al, GABARAPL2 in neurodegenerative disease (2022)](https://pubmed.ncbi.nlm.nih.gov/35241735/)