IRGM
Domain
The G5 motif of the IRG-type G domain is missing because the IRGM protein is truncated in anthropoids.
Function
Immunity-related GTPase that plays important roles in innate immunity and inflammatory response (PubMed:16888103, PubMed:19165925, PubMed:25891078). Acts as a dynamin-like protein that binds to intracellular membranes and promotes remodeling and trafficking of those membranes (By similarity). Required for clearance of acute protozoan and bacterial infections by interacting with autophagy and lysosome regulatory proteins, thereby promoting the fusion of phagosomes with lysosomes for efficient degradation of cargo including microbes (PubMed:16888103, PubMed:25891078, PubMed:29420192, PubMed:32939830). Regulates selective autophagy, including xenophagy and mitophagy, both directly and indirectly (PubMed:16888103, PubMed:25891078, PubMed:29420192, PubMed:32939830). Directly regulates autophagy by acting as a molecular adapter that promotes the coassembly of the core autophagy machinery to mediate antimicrobial defense: IRGM (1) activates AMPK, which in turn phosphorylates ULK1 and BECN1 to induce autophagy, (2) promotes the coassembly of ULK1 and BECN1, enhancing BECN1-interacting partners and (3) influences the composition of the BECN1 complex, by competing with the negative regulators BCL2 and RUBCN, to trigger autophagy (PubMed:25891078). Also activates autophagy by promoting recruitment of STX17 to autophagosomes (PubMed:29420192). In collaboration with ATG8 proteins, regulate lysosomal biogenesis, a fundamental process for any autophagic pathway, by promoting TFEB dephosphorylation (PubMed:32753672). Also modulates autophagy by assisting with autophagosome formation and preventing lysosomal deacidification (By similarity). While activating autophagy, acts as a key negative regulator of the inflammatory and interferon responses both by (1) promoting mitophagy and (2) mediating autophagy-dependent degradation of effectors of the inflammatory response (PubMed:30612879, PubMed:32715615, PubMed:36221902). Promotes degradation of damaged and IFNG/IFN-gamma-stressed mitochondria via mitophagy, preventing cytosolic release of ligands that activate inflammation (PubMed:32715615). Acts as a suppressor of inflammation by promoting recruitment of inflammation effectors, such as CGAS, RIGI/RIG-I and NLRP3, to autophagosome membranes, leading to their SQSTM1/p62-dependent autophagic degradation (PubMed:30612879, PubMed:32715615). Also directly inhibits assembly of the NLRP3 inflammasome by preventing the association between NLRP3 and PYCARD (PubMed:30612879). Acts as a negative regulator of antiviral innate immune response by suppressing the RIPK2-dependent pro-inflammatory response: mediates recruitment of RIPosomes, composed of RIPK2 and NOD1 or NOD2, to autophagosome membranes, promoting their SQSTM1/p62-dependent autophagic degradation (PubMed:34467632, PubMed:36221902).
Isoform IRGMd
Acts as a positive regulator of mitophagy in response to intracellular mycobacteria infection: specifically binds cardiolipin, leading to its translocation to mitochondria, where it promotes affected mitochondrial fission and mitophagy.
(Microbial infection) Following infection by hepatitis C virus (HCV), promotes HCV-triggered membrane remodeling, leading to autophagy and Golgi fragmentation, a step required for HCV replication.
Involvement in disease
Inflammatory bowel disease 19
IBD19
A chronic, relapsing inflammation of the gastrointestinal tract with a complex etiology. It is subdivided into Crohn disease and ulcerative colitis phenotypes. Crohn disease may affect any part of the gastrointestinal tract from the mouth to the anus, but most frequently it involves the terminal ileum and colon. Bowel inflammation is transmural and discontinuous; it may contain granulomas or be associated with intestinal or perianal fistulas. In contrast, in ulcerative colitis, the inflammation is continuous and limited to rectal and colonic mucosal layers; fistulas and granulomas are not observed. Both diseases include extraintestinal inflammation of the skin, eyes, or joints.
None
Disease susceptibility is associated with variants affecting the gene represented in this entry.
Post-translational modifications
Ubiquitinated via 'Lys-63'-linked polyubiquitination in a NOD2-dependent process. 'Lys-63'-linked polyubiquitination is required for interactions with the core autophagy factors.
Sequence Similarities
Belongs to the TRAFAC class dynamin-like GTPase superfamily. IRG family.
Tissue Specificity
Widely expressed (at protein level) (PubMed:16888103). Expressed in several tissues including colon, small bowel and peripheral blood leukocytes (PubMed:17554261).
Cellular localization
- Golgi apparatus membrane
- Cell membrane
- Cytoplasmic vesicle
- Phagosome membrane
- Cytoplasmic vesicle
- Autophagosome membrane
- Lysosome membrane
- Late endosome membrane
- Mitochondrion membrane
- Cell projection
- Phagocytic cup
- Behaves like an integral membrane protein. Recruited to the plasma membrane around forming phagocytic cups, it remains associated with maturing phagosomes. Association with phagosomes is dependent on nucleotide-binding but is IFNG-independent. Also detected in late endosomes and lysosomes.
- Isoform IRGMd
- Mitochondrion
Alternative names
IFI1, IRGM1, LRG47, IRGM, Immunity-related GTPase family M protein, Immunity-related GTPase family M protein 1, Interferon-inducible protein 1, LPS-stimulated RAW 264.7 macrophage protein 47 homolog, LRG-47