CD18 integrin beta 2 subunit is a 90 kDa type I transmembrane protein expressed on all leucocytes. CD18 can combine with integrin molecules CD11a-c to form heterodimers at the cell surface, and these heterodimers are known to participate in the process of cell adhesion as well as cell-surface mediated signaling. CD18 forms heterodimers with four types of CD11 molecule to constitute leukocyte (beta2) integrins: alphaLbeta2 (CD11a/CD18, LFA-1), alphaMbeta2 (CD11b/CD18, Mac-1, CR3), alphaXbeta2 (CD11c/CD18) and alphaDbeta2 (CD11d/CD18). In most cases, the response mediated by the integrin is a composite of the functions of its individual subunits, and these integrins are essential for proper leukocyte migration, mediating intercellular contacts. Absence of CD18 leads to leukocyte adhesion deficiency-1, severe reduction of CD18 expression leads to the development of a psoriasiform skin disease. CD18 is also a target of Mannheimia (Pasteurella) haemolytica leukotoxin and is sufficient to mediate leukotoxin-mediated cytolysis. Defects in the CD18 gene are the cause of leukocyte adhesion deficiency type I (LAD1). Two transcript variants encoding the CD18 protein have been identified.
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Protein Aliases: CD18; CD18 leukocyte adhesion molecule; cell surface adhesion glycoprotein (LFA-1/CR3/P150,959 beta subunit precursor); Cell surface adhesion glycoproteins LFA-1/CR3/p150,95 subunit beta; complement component 3 receptor 3 and 4 subunit; complement receptor C3 beta-subunit; Complement receptor C3 subunit beta; integrin beta chain, beta 2; Integrin beta-2; integrin, beta 2 (antigen CD18 (p95), lymphocyte function-associated antigen 1; integrin, beta 2 (antigen CD18 (p95), lymphocyte function-associated antigen 1; macrophage antigen 1 (mac-1) beta subunit); integrin, beta 2 (complement component 3 receptor 3 and 4 subunit); leukocyte cell adhesion molecule CD18; leukocyte-associated antigens CD18/11A, CD18/11B, CD18/11C; lymphocyte function associated antigen 1; Mac-1 beta; macrophage antigen 1 (mac-1) beta subunit); macrophage antigen-1 beta
Gene Aliases: 2E6; AI528527; CD18; ITGB2; LAD; LCAMB; LFA-1; Lfa1; MAC-1; MF17; MFI7
Molecular Function: integrin