MAP1LC3B

Ubiquitin-like modifier involved in formation of autophagosomal vacuoles (autophagosomes) (PubMed:20418806, PubMed:23209295, PubMed:28017329). Plays a role in mitophagy which contributes to regulate mitochondrial quantity and quality by eliminating the mitochondria to a basal level to fulfill cellular energy requirements and preventing excess ROS production (PubMed:23209295, PubMed:28017329). In response to cellular stress and upon mitochondria fission, binds C-18 ceramides and anchors autophagolysosomes to outer mitochondrial membranes to eliminate damaged mitochondria (PubMed:22922758). 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:20418806, PubMed:23209295, PubMed:28017329). Promotes primary ciliogenesis by removing OFD1 from centriolar satellites via the autophagic pathway (PubMed:24089205). 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). Upon nutrient stress, directly recruits cofactor JMY to the phagophore membrane surfaces and promotes JMY's actin nucleation activity and autophagosome biogenesis during autophagy (PubMed:30420355).

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:15355958, PubMed:20818167, PubMed:29458288, PubMed:30661429, PubMed:31315929). 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:29458288, 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). 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:28395732, PubMed:31722778). RavZ is also able to mediate delipidation of ATG8 proteins conjugated to phosphatidylserine (PS) (PubMed:33909989).

Phosphorylation by PKA inhibits conjugation of phosphatidylethanolamine (PE) (PubMed:22948227). Interaction with MAPK15 reduces the inhibitory phosphorylation and increases autophagy activity (PubMed:22948227).

Ubiquitinated by BIRC6; this activity is inhibited by DIABLO/SMAC.

Belongs to the ATG8 family.

Most abundant in heart, brain, skeletal muscle and testis. Little expression observed in liver.

• Cytoplasmic vesicle
• Autophagosome membrane
• Lipid-anchor
• Endomembrane system
• Lipid-anchor
• Mitochondrion membrane
• Lipid-anchor
• Cytoplasm
• Cytoskeleton
• Cytoplasmic vesicle
• LC3-II binds to the autophagic membranes. LC3-II localizes with the mitochondrial inner membrane during Parkin-mediated mitophagy (PubMed:28017329). Localizes also to discrete punctae along the ciliary axoneme.

MAP1ALC3, MAP1LC3B, Microtubule-associated proteins 1A/1B light chain 3B, Autophagy-related protein LC3 B, Autophagy-related ubiquitin-like modifier LC3 B, MAP1 light chain 3-like protein 2, MAP1A/MAP1B light chain 3 B, Microtubule-associated protein 1 light chain 3 beta, MAP1A/MAP1B LC3 B

• entrezGene:81631
• entrezGene:84557
• omim:609604
• omim:601242
• swissprot:Q9GZQ8
• swissprot:Q9H492

Proteins

Oncology

• Immuno-oncology
• Immunology & Infectious Disease

14688Da