Integrin alpha M

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Integrin, alpha M (complement component 3 receptor 3 subunit)
Protein ITGAM PDB 1bho.png
PDB rendering based on 1bho.
Available structures
PDB Ortholog search: PDBe, RCSB
Symbols ITGAM ; CD11B; CR3A; MAC-1; MAC1A; MO1A; SLEB6
External IDs OMIM120980 MGI96607 HomoloGene526 ChEMBL: 3826 GeneCards: ITGAM Gene
RNA expression pattern
PBB GE ITGAM 205786 s at tn.png
More reference expression data
Species Human Mouse
Entrez 3684 16409
Ensembl ENSG00000169896 ENSMUSG00000030786
UniProt P11215 P05555
RefSeq (mRNA) NM_000632 NM_001082960
RefSeq (protein) NP_000623 NP_001076429
Location (UCSC) Chr 16:
31.26 – 31.33 Mb
Chr 7:
128.06 – 128.13 Mb
PubMed search [1] [2]

Integrin alpha M (ITGAM) is one protein subunit that forms the heterodimeric integrin alpha-M beta-2 (αMβ2) molecule, also known as macrophage-1 antigen (Mac-1) or complement receptor 3 (CR3).[1] ITGAM is also known as CR3A, and cluster of differentiation molecule 11B (CD11B). The second chain of αMβ2 is the common integrin β2 subunit known as CD18, and integrin αMβ2 thus belongs to the β2 subfamily (or leukocyte) integrins.[2]

αMβ2 is expressed on the surface of many leukocytes involved in the innate immune system, including monocytes, granulocytes, macrophages, and natural killer cells.[1] It mediates inflammation by regulating leukocyte adhesion and migration and has been implicated in several immune processes such as phagocytosis, cell-mediated cytotoxicity, chemotaxis and cellular activation.[1] It is involved in the complement system due to its capacity to bind inactivated complement component 3b (iC3b).[3] The ITGAM (alpha) subunit of integrin αMβ2 is directly involved in causing the adhesion and spreading of cells but cannot mediate cellular migration without the presence of the β2 (CD18) subunit.[1]

In genomewide association studies, single nucleotide polymorphisms in ITGAM had the strongest association with systemic lupus erythematosus, with an odds ratio of 1.65 for the T allele of rs9888739 and lupus.[4][5]

In histopathology, immunohistochemistry with antibodies against CD11B is frequently used to identify macrophages and microglia.

See also[edit]


  1. ^ a b c d Solovjov D, Pluskota E, Plow E (2005). "Distinct roles for the alpha and beta subunits in the functions of integrin alphaMbeta2". J Biol Chem 280 (2): 1336–45. doi:10.1074/jbc.M406968200. PMID 15485828. 
  2. ^ Larson R, Springer T (1990). "Structure and function of leukocyte integrins". Immunol Rev 114: 181–217. doi:10.1111/j.1600-065X.1990.tb00565.x. PMID 2196220. 
  3. ^ Arnaout M, Todd R, Dana N, Melamed J, Schlossman S, Colten H (1983). "Inhibition of phagocytosis of complement C3- or immunoglobulin G-coated particles and of C3bi binding by monoclonal antibodies to a monocyte-granulocyte membrane glycoprotein (Mol)". J Clin Invest 72 (1): 171–9. doi:10.1172/JCI110955. PMC 1129172. PMID 6874946. 
  4. ^ Mary K. Crow (February 28, 2008). "Collaboration, Genetic Associations, and Lupus Erythematosus". N Engl J Med 358 (9): 956–961. doi:10.1056/NEJMe0800096. PMID 18204099. 
  5. ^ Geoffrey Hom, Robert R. Graham, Barmak Modrek; et al. (February 28, 2008). "Association of Systemic Lupus Erythematosus with C8orf13–BLK and ITGAM–ITGAX". N Engl J Med 358 (9): 900–909. doi:10.1056/NEJMoa0707865. PMID 18204098. 

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