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Function

Ubiquitin-like modifier involved in formation of autophagosomal vacuoles (autophagosomes) (PubMed:20713600, PubMed:24290141). While LC3s are involved in elongation of the phagophore membrane, the GABARAP/GATE-16 subfamily is essential for a later stage in autophagosome maturation (PubMed:20713600). Through its interaction with the reticulophagy receptor TEX264, participates in the remodeling of subdomains of the endoplasmic reticulum into autophagosomes upon nutrient stress, which then fuse with lysosomes for endoplasmic reticulum turnover (PubMed:31006537, PubMed:31006538).

Post-translational modifications

The precursor molecule is cleaved by ATG4 (ATG4A, ATG4B, ATG4C or ATG4D) to expose the glycine at the C-terminus and form the cytosolic form, LC3-I (PubMed:15187094, PubMed:30661429). The processed form is then activated by APG7L/ATG7, transferred to ATG3 and conjugated to phosphatidylethanolamine (PE) phospholipid to form the membrane-bound form, LC3-II (PubMed:15187094). During non-canonical autophagy, the processed form is conjugated to phosphatidylserine (PS) phospholipid (PubMed:33909989). ATG4 proteins also mediate the delipidation of PE-conjugated forms (PubMed:32686895, PubMed:33909989). In addition, ATG4B and ATG4D mediate delipidation of ATG8 proteins conjugated to PS during non-canonical autophagy (PubMed:33909989). ATG4B constitutes the major protein for proteolytic activation (PubMed:30661429, PubMed:33909989). ATG4D is the main enzyme for delipidation activity (By similarity).

(Microbial infection) The Legionella effector RavZ is a deconjugating enzyme that hydrolyzes the amide bond between the C-terminal glycine residue and an adjacent aromatic residue in ATG8 proteins conjugated to phosphatidylethanolamine (PE), producing an ATG8 protein that is resistant to reconjugation by the host machinery due to the cleavage of the reactive C-terminal glycine (PubMed:23112293, PubMed:31722778, PubMed:32686895). RavZ is also able to mediate delipidation of ATG8 proteins conjugated to phosphatidylserine (PS) (PubMed:33909989).

Phosphorylation at Ser-12 by PKA inhibits conjugation to phosphatidylethanolamine (PE).

Sequence similarities

Belongs to the ATG8 family.

Tissue specificity

Most abundant in heart, brain, liver, skeletal muscle and testis but absent in thymus and peripheral blood leukocytes.

Cellular localization

  • Cytoplasmic vesicle
  • Autophagosome membrane
  • Lipid-anchor
  • Endomembrane system
  • Lipid-anchor
  • Cytoplasm
  • Cytoskeleton
  • LC3-II binds to the autophagic membranes.

Alternative names

Microtubule-associated proteins 1A/1B light chain 3A, Autophagy-related protein LC3 A, Autophagy-related ubiquitin-like modifier LC3 A, MAP1 light chain 3-like protein 1, MAP1A/MAP1B light chain 3 A, Microtubule-associated protein 1 light chain 3 alpha, MAP1A/MAP1B LC3 A, MAP1LC3A

Target type

Proteins

Primary research area

Immunology & Infectious Disease

Molecular weight

14272Da