Atg4A 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.
| ATG4A Protein | |
|---|---|
| Protein Name | Autophagin-2, Cysteine protease ATG4A |
| Gene | ATG4A |
| UniProt ID | Q9Y4P5 |
| PDB ID | 2DUX, 2HOE |
| Molecular Weight | 52.5 kDa |
| Subcellular Localization | Cytoplasm, Nucleus |
| Protein Family | Cysteine protease, ATG4 family |
| Aliases | APG4A, AUTL2, APE2 |
| Associated Diseases | Alzheimer's Disease, Parkinson's Disease, ALS, Huntington's Disease |
ATG4A (Autophagy Related 4A Cysteine Peptidase) is a member of the ATG4 family of cysteine proteases that play essential roles in the autophagy machinery. Also known as Autophagin-2, ATG4A is one of four mammalian ATG4 proteases (ATG4A, ATG4B, ATG4C, ATG4D) that process LC3/GABARAP family proteins during autophagosome formation. ATG4A specifically cleaves the C-terminal amino acids from LC3/GABARAP proteins, converting them from pro-LC3 to the active form (LC3-I) and then facilitating the lipidation reaction that generates LC3-II, which is essential for autophagosome biogenesis. Dysregulation of ATG4A and autophagy is implicated in Alzheimer's disease, Parkinson's disease, ALS, and Huntington's disease.
ATG4A is a 52.5 kDa cysteine protease with characteristic protease domain architecture:
| Domain | Position | Function |
|---|---|---|
| N-terminal regulatory domain | 1-150 | Substrate recognition, regulatory elements |
| Protease domain | 150-393 | Catalytic activity, cysteine protease |
| C-terminal domain | 393-454 | Dimerization, substrate binding |
ATG4A catalyzes two essential reactions in the autophagy pathway:
Pro-LC3 processing (ATG4A, ATG4B)
Delipidation (primarily ATG4B, some ATG4A)
| Substrate | Processing by ATG4A | Function |
|---|---|---|
| LC3A | Yes | Autophagosome formation |
| LC3B | Yes | Ubiquitin-like conjugation |
| LC3C | Limited | Selective autophagy |
| GABARAP | Yes | Autophagosome closure |
| GABARAPL1 | Yes | Early steps |
| GABARAPL2 | Yes | Cargo recognition |
| Function | Mechanism | Significance |
|---|---|---|
| Autophagosome formation | LC3 processing | Core autophagy |
| Selective autophagy | Substrate recognition | Quality control |
| Mitophagy | Parkin recruitment | Mitochondrial clearance |
| Lipophagy | Lipid droplet clearance | Metabolic regulation |
| Ribophagy | Ribosome clearance | Nutrient stress |
Autophagy is significantly impaired in Alzheimer's disease, and ATG4A dysfunction contributes to pathology:
| Approach | Mechanism | Development Stage |
|---|---|---|
| ATG4A activators | Enhance LC3 processing | Research |
| Autophagy inducers | mTOR inhibition, AMPK activation | Clinical trials |
| ATG4A gene therapy | Increase expression | Experimental |
| Small molecule enhancers | Allosteric activation | Preclinical |
| Agent | Target | Status |
|---|---|---|
| Rapamycin | mTORC1 | Research |
| Metformin | AMPK | Clinical trials |
| Trehalose | TFEB activation | Research |
| Lithium | IMPase, autophagy | Research |
| Vitamin D | Autophagy genes | Research |
| Biomarker | Sample | Changes in Disease |
|---|---|---|
| LC3-II/I ratio | Brain tissue | ↑ or dysregulated |
| p62/SQSTM1 | Brain tissue | Accumulation |
| ATG4A activity | Cells | ↓ in disease |
| Autophagic flux | CSF | Impaired |
The study of Atg4A 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.
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[7] Uemura T, et al. ATG4 proteases as therapeutic targets. Trends Pharmacol Sci. 2024;45(3):215-228. PMID:38215534