ATG13 Protein

ATG13 Protein

Introduction

ATG13 (Autophagy Related 13) is a key regulator of autophagy, a critical cellular process for degrading and recycling damaged organelles and protein aggregates. The ATG13 protein is part of the ULK1 complex (ULK1-ATG13-FIP200-ATG101), which initiates autophagosome formation in response to cellular energy status and nutrient availability. This protein plays a crucial role in neuronal health and is implicated in neurodegenerative diseases through its function in mitophagy and aggregate clearance. [@mizushima2009]

ATG13 Protein

Introduction

ATG13 (Autophagy Related 13) is a key regulator of autophagy, a critical cellular process for degrading and recycling damaged organelles and protein aggregates. The ATG13 protein is part of the ULK1 complex (ULK1-ATG13-FIP200-ATG101), which initiates autophagosome formation in response to cellular energy status and nutrient availability. This protein plays a crucial role in neuronal health and is implicated in neurodegenerative diseases through its function in mitophagy and aggregate clearance. [@mizushima2009]

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">Autophagy Related 13 Protein</th></tr>
<tr><td><strong>Protein Name</strong></td><td>ATG13</td></tr>
<tr><td><strong>Gene</strong></td><td><a href="/genes/atg13">ATG13</a></td></tr>
<tr><td><strong>UniProt ID</strong></td><td><a href="https://www.uniprot.org/uniprot/Q9UQL6">Q9UQL6</a></td></tr>
<tr><td><strong>PDB Structures</strong></td><td>5C6Z, 5ZVN, 5G0F</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>52 kDa</td></tr>
<tr><td><strong>Subcellular Localization</strong></td><td>Cytoplasm, Autophagosome</td></tr>
<tr><td><strong>Protein Family</strong></td><td>ATG13 family</td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/atherosclerosis" style="color:#ef9a9a">Atherosclerosis</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/cardiovascular" style="color:#ef9a9a">Cardiovascular</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">108 edges</a></td>
</tr>
</table>
</div>

Overview

ATG13 is a 459 amino acid protein with an intrinsically disordered region that serves as a scaffold for the ULK1 complex. The protein contains an LC3-interacting region (LIR) that binds to LC3/GABARAP proteins during autophagy initiation. ATG13 also has a domain that interacts with FIP200 and ATG101 to form the stable ULK1 complex. [@ganley2011]

Structure

Domain Architecture

Key Structural Features

| Feature | Location | Function |
|---------|----------|----------|
| ULK1-binding domain | N-terminus | Binds and activates ULK1 kinase |
| FIP200-interacting region | Central | Scaffold for complex formation |
| ATG101-binding site | Central | Stabilizes ULK1 complex |
| LIR (LC3-interacting region) | aa 350-400 | Binds LC3/GABARAP proteins |
| Multiple phosphorylation sites | Throughout | Regulation by mTOR/AMPK |

Normal Function

ULK1 Complex Assembly and Regulation

ATG13 is a critical regulator of autophagy initiation. As part of the ULK1 complex (ULK1-ATG13-FIP200-ATG101), ATG13 senses cellular energy status via [AMPK](/mechanisms/ampk-signaling-pathway) and nutrient status via [mTOR](/mechanisms/mtor-signaling-pathway). When nutrients are scarce or energy is low, ATG13 promotes ULK1 kinase activation, leading to downstream autophagy induction. [@itakura2012]

Complex regulation:

Neuronal Function

In [neurons](/entities/neurons), ATG13-mediated autophagy is essential for: [@hong2017]

• Synaptic protein turnover: Degradation of old synaptic components
• Mitochondrial quality control: [Mitophagy](/mechanisms/pink1-parkin-mitophagy-pathway-parkinsons) removes damaged mitochondria
• Aggregate clearance: Removes misfolded proteins and aggregates
• Axonal transport: Autophagosomes move along axons to deliver cargo to lysosomes

Autophagy Initiation Cascade

Role in Disease

Dysregulation of ATG13 contributes to neurodegenerative diseases through impaired autophagy: [@nixon2014]

Parkinson's Disease

• Impaired mitophagy leads to accumulation of damaged mitochondria in dopaminergic neurons
• PINK1/PARKIN pathway dysfunction: ATG13 interacts with PINK1
• Alpha-synuclein clearance is reduced
• Dopaminergic neuron vulnerability: High energy demand makes neurons dependent on mitophagy

Alzheimer's Disease

• Reduced autophagy impairs clearance of [amyloid-beta](/proteins/amyloid-beta) and [tau](/proteins/tau) aggregates
• Synaptic dysfunction: Impaired clearance of damaged synaptic proteins
• Neuronal death: Accumulation of toxic protein aggregates

Amyotrophic Lateral Sclerosis (ALS)

• Defective autophagy contributes to [TDP-43 proteinopathy](/mechanisms/tdp-43-proteinopathy)
• Motor neuron vulnerability: High protein turnover demands
• Aggregate accumulation: TDP-43 inclusions not cleared

Huntington's Disease

• Impaired clearance of mutant [huntingtin protein](/proteins/huntingtin)
• Macroautophagy defects: Failed cargo recognition
• Neuronal dysfunction: Aggregate-mediated toxicity

Mitophagy Specific Role

ATG13 plays a direct role in mitophagy through its interaction with the PINK1-PARKIN pathway: [@wang2019]

• PINK1 stabilization on damaged mitochondria triggers PARKIN recruitment
• ATG13 assists in the formation of mitophagosomes
• LC3 lipidation is required for autophagosome membrane expansion
• Damaged mitochondria are selectively eliminated

Therapeutic Targeting

Pharmacological Approaches

| Target | Agent | Mechanism | Status |
|--------|-------|-----------|--------|
| mTOR inhibitors | Rapamycin, Everolimus | Induce autophagy via ATG13/ULK1 | Approved |
| ULK1 activators | AZD8055, Torin1 | Activate autophagy initiation | Research |
| Autophagy inducers | Trehalose, Spermidine, Lithium | Multiple pathways | Preclinical |

Experimental Strategies

• ATG13 phosphorylation modulators: Develop compounds targeting ATG13 kinases/phosphatases
• LIR domain agonists: Promote LC3 interaction
• Gene therapy: AAV-mediated ATG13 expression

Natural Compounds

• Trehalose: Induces TFEB and autophagy
• Spermin: Promotes autophagy flux
• Lithium: Inhibits GSK-3β, activates autophagy
• Resveratrol: Activates SIRT1, enhances autophagy

Signaling Integration

Cross-linking to Related Pages

• [ATG13 Gene](/genes/atg13) - Gene page
• [Autophagy](/mechanisms/autophagy) - Mechanism page
• [ULK1 Complex](/mechanisms/ulk1-complex) - Related pathway
• [Parkinson's Disease](/diseases/parkinsons-disease) - Disease relevance
• [Alzheimer's Disease](/diseases/alzheimers-disease) - Disease relevance
• [ALS](/diseases/amyotrophic-lateral-sclerosis) - Disease relevance
• [PINK1-PARKIN Pathway](/mechanisms/pink1-parkin-mitophagy-pathway-parkinsons) - Mitophagy

See Also

• [ATG13 Gene](/genes/atg13)
• [Autophagy](/mechanisms/autophagy)
• [ULK1 Complex](/mechanisms/ulk1-complex)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Mitophagy](/mechanisms/pink1-parkin-mitophagy-pathway-parkinsons)

External Links

• [UniProt - ATG13](https://www.uniprot.org/uniprot/Q9UQL6)
• [PDB - ATG13 Structure](https://www.ebi.ac.uk/pdbe/entry/pdb/5g0f)
• [NCBI Protein - ATG13](https://www.ncbi.nlm.nih.gov/protein/NP_057313.1)
• [GeneCards - ATG13](https://www.genecards.org/cgi-bin/carddisp.pl?gene=ATG13)

References