ATG3

In molecular biology, autophagy related 3 (Atg3) is the E2 enzyme for the LC3 lipidation process.^[5] It is essential for autophagy. The super protein complex, the Atg16L complex, consists of multiple Atg12-Atg5 conjugates. Atg16L has an E3-like role in the LC3 lipidation reaction. The activated intermediate, LC3-Atg3 (E2), is recruited to the site where the lipidation takes place.^[6]

AliasesATG3, APG3-LIKE, APG3, autophagy related 3, APG3L, PC3-96

External IDsOMIM: 609606; MGI: 1915091; GeneCards: ATG3

PDBOrtholog search: PDBe RCSB

Chr.Chromosome 3 (human)^[1]

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ATG3
Identifiers
Aliases	ATG3, APG3-LIKE, APG3, autophagy related 3, APG3L, PC3-96
External IDs	OMIM: 609606; MGI: 1915091; GeneCards: ATG3
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 4NAW
Gene location (Human) Chr. Chromosome 3 (human)[1] Band 3q13.2 Start 112,532,510 bp[1] End 112,562,046 bp[1]
Gene location (Mouse) Chr. Chromosome 16 (mouse)[2] Band 16|16 B5 Start 44,979,148 bp[2] End 45,008,901 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in monocyte sperm trabecular bone jejunal mucosa corpus callosum bone marrow external globus pallidus inferior ganglion of vagus nerve mucosa of sigmoid colon pons Top expressed in parotid gland granulocyte left lobe of liver epithelium of lens mesenteric lymph nodes deep cerebellar nuclei medial vestibular nucleus cerebellar vermis lobe of cerebellum stroma of bone marrow More reference expression data BioGPS n/a
Gene ontology Molecular function ubiquitin-like protein transferase activity enzyme binding Atg12 transferase activity protein binding Atg8 ligase activity transferase activity Cellular component cytoplasm cytosol cytoplasmic ubiquitin ligase complex Biological process regulation of cilium assembly mitochondrial fragmentation involved in apoptotic process autophagy protein transport autophagy of nucleus autophagy of mitochondrion autophagosome assembly protein ubiquitination protein targeting to membrane macroautophagy negative regulation of phagocytosis Sources:Amigo / QuickGO
Orthologs Databases NCBI: entry; OMA: entry Species Human Mouse Entrez 64422 67841 Ensembl ENSG00000144848 ENSMUSG00000022663 UniProt Q9NT62 Q9CPX6 RefSeq (mRNA) NM_001278712 NM_022488 NM_026402 NM_001356366 RefSeq (protein) NP_001265641 NP_071933 NP_080678 NP_001343295 Location (UCSC) Chr 3: 112.53 – 112.56 Mb Chr 16: 44.98 – 45.01 Mb PubMed search [3] [4]
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Atg3 catalyses the conjugation of Atg8 and phosphatidylethanolamine (PE). Atg3 has an alpha/beta-fold, and its core region is topologically similar to canonical E2 enzymes. Atg3 has two regions inserted in the core region and another with a long alpha-helical structure that protrudes from the core region as far as 30 A.^[7] It interacts with atg8 through an intermediate thioester bond between Cys-288 and the C-terminal Gly of atg8. It also interacts with the C-terminal region of the E1-like atg7 enzyme.

Autophagocytosis is a starvation-induced process responsible for transport of cytoplasmic proteins to the lysosome/vacuole. Atg3 is a ubiquitin like modifier that is topologically similar to the canonical E2 enzyme.^[8] It catalyses the conjugation of Atg8 and phosphatidylethanolamine.^[9]

Atg3 consists of three domains, an N-terminal domain, a catalytic domain and a C-terminal domain. The catalytic domain contains a cysteine residue within an HPC motif, this is the putative active-site residue for recognition of the Apg5 subunit of the autophagosome complex.^[10] The small C-terminal domain is likely to be a distinct binding region for the stability of the autophagosome complex.^[11] It carries a highly characteristic conserved FLKF sequence motif.