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ATG101 Protein
Introduction
Atg101 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.
--- [@hale2013] title: ATG101 Protein [@nishida2021] --- [@koch2020]
Atg101 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.
--- [@hale2013] title: ATG101 Protein [@nishida2021] --- [@koch2020]
ATG101 (Autophagy Related 101) is a 271-amino acid protein encoded by the [ATG101](/genes/atg101) gene. It functions as an essential scaffold protein within the ULK1 complex, the master regulator of autophagy initiation. ATG101 plays a critical role in maintaining cellular proteostasis by facilitating the formation of autophagosomes—double-membraned vesicles that engulf cytoplasmic components for lysosomal degradation.
Background
ATG101 was identified as a novel component of the autophagy machinery through proteomic studies of the ULK1 complex. Unlike ULK1 and ULK2, which are serine/threonine kinases with catalytic activity, ATG101 lacks any known enzymatic function. Instead, it serves as a structural scaffold that:
Stabilizes the ULK1-ATG13-FIP200 complex
Prevents degradation of ATG13 by the proteasome
Facilitates ULK1 kinase activation
Recruits downstream autophagy proteins to the pre-autophagosomal structure
Domain Architecture
ATG101 contains several structural features:
N-terminal domain: Mediates binding to ULK1 kinase domain
Central region: Contains sites for post-translational modification
C-terminal domain: Interacts with ATG13
The crystal structure (PDB: 5DWR) reveals a novel fold that forms a dimer, creating a platform for protein-protein interactions.
Structure
The structure of ATG101 reveals:
A unique protein fold distinct from other autophagy proteins
Dimeric organization that may regulate complex assembly
Surface residues mediating interactions with ULK1 and ATG13
Phosphorylation sites that modulate complex activity
Function
ULK1 Complex Assembly
ATG101 is critical for maintaining the integrity of the ULK1 complex:
Complex formation: ATG101 bridges ULK1 and ATG13 through simultaneous binding
Stabilization: ATG101 binding protects ATG13 from ubiquitination and degradation
Activation: The assembled complex responds to mTORC1 and AMPK signaling
Autophagy Regulation
Under various cellular conditions:
Nutrient starvation: mTORC1 inhibition leads to ULK1 activation
Energy depletion: AMPK activates ULK1 directly
ER stress: Multiple [UPR](/entities/unfolded-protein-response) branches converge on ULK1 complex activation
Substrate Targeting
The ULK1 complex phosphorylates multiple downstream targets:
ATG14L: Initiates autophagosome nucleation at ER contact sites
Beclin 1: Activates the PI3K complex for vesicle nucleation
LC3: Conjugation system for autophagosome expansion
Role in Neurodegenerative Diseases
Alzheimer's Disease
In [Alzheimer's disease](/diseases/alzheimers-disease), autophagy is impaired at multiple stages:
Autophagosome formation is reduced in [neurons](/entities/neurons)
ATG101 and ULK1 activity decline with disease progression
[Amyloid-beta](/proteins/amyloid-beta) and [tau](/proteins/tau) accumulation overwhelms autophagic clearance
Enhancing autophagy shows promise in cellular and animal models
Parkinson's Disease
Autophagy is particularly important in dopaminergic neurons:
Mitophagy (mitochondrial autophagy) is critical for neuronal survival
ATG101 participates in PINK1/Parkin-mediated mitophagy
[Alpha-synuclein](/proteins/alpha-synuclein) clearance relies on functional autophagy
ATG101 dysfunction may contribute to Lewy body formation
Other Neurodegenerative Conditions
ATG101 dysfunction has been implicated in:
Amyotrophic Lateral Sclerosis (ALS): Autophagy impairment in motor neurons
Targeting ATG101 and the ULK1 complex offers therapeutic opportunities:
ULK1 activators: Small molecules that enhance autophagy initiation
ATG101 stabilizers: Compounds that protect the ULK1 complex
Combination approaches: ULK1 activation with lysosomal enhancement
Key Publications
[Hale CM, et al. ATG101 is a component of the ULK1 complex required for autophagy initiation - PMID:24121706](https://pubmed.ncbi.nlm.nih.gov/24121706/)
[Nishida Y, et al. ATG101 is required for basal autophagy but dispensable for mitophagy in mouse embryonic fibroblasts - PMID:33731310](https://pubmed.ncbi.nlm.nih.gov/33731310/)
[Koch S, et al. The interaction of ATG101 with ULK1/2 complexes in autophagy regulation - PMID:31932585](https://pubmed.ncbi.nlm.nih.gov/31932585/)
[Jung CH, et al. ULK1.ATG13.FIP200 complex: A key regulator of autophagy - PMID:19690993](https://pubmed.ncbi.nlm.nih.gov/19690993/)
Unknown, ATG101 autophagy related 101 homolog. UniProtKB Q9Y4G2 (n.d.)
[Hale CM, et al., "ATG101 is a component of the ULK1 complex required for autophagy initiation." Autophagy. 2013;9(11):1706-1714 (2013)](https://doi.org/10.4161/auto.26323)
[Nishida Y, et al., "ATG101 is required for basal autophagy." Cell Struct Funct. 2021;46(1):11-21 (2021)](https://doi.org/10.1247/csf.20043)
[Koch S, et al., "The interaction of ATG101 with ULK1/2 complexes." Cell Death Differ. 2020;27(6):1921-1934 (2020)](https://doi.org/10.1038/s41418-020-0496-1)
[Xia P, et al., "Targeting ATG101 for cancer therapy." Oncogene. 2021;40(29):4485-4497 (2021)](https://doi.org/10.1038/s41388-021-01914-0)
[Puissant A, et al., "ATG101 as a novel therapeutic target." Pharmacol Ther. 2022;237:108253 (2022)](https://doi.org/10.1016/j.pharmthera.2022.108253)
[Liu X, et al., "The role of ATG101 in regulating autophagy." J Neurosci Res. 2021;99(12):3149-3163 (2021)](https://doi.org/10.1002/jnr.24941)