| Structural highlights
Disease
[ITB2_HUMAN] Defects in ITGB2 are the cause of leukocyte adhesion deficiency type 1 (LAD1) [MIM:116920]. LAD1 patients have recurrent bacterial infections and their leukocytes are deficient in a wide range of adhesion-dependent functions.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11]
Function
[ITB2_HUMAN] Integrin alpha-L/beta-2 is a receptor for ICAM1, ICAM2, ICAM3 and ICAM4. Integrins alpha-M/beta-2 and alpha-X/beta-2 are receptors for the iC3b fragment of the third complement component and for fibrinogen. Integrin alpha-X/beta-2 recognizes the sequence G-P-R in fibrinogen alpha-chain. Integrin alpha-M/beta-2 recognizes P1 and P2 peptides of fibrinogen gamma chain. Integrin alpha-M/beta-2 is also a receptor for factor X. Integrin alpha-D/beta-2 is a receptor for ICAM3 and VCAM1. Triggers neutrophil transmigration during lung injury through PTK2B/PYK2-mediated activation.[12]
Publication Abstract from PubMed
Integrins mediate cell adhesion in response to activation signals that trigger conformational changes within their ectodomain. It is thought that a compact bent conformation of the molecule represents its physiological low affinity state and extended conformations its active state. We have determined the structure of two integrin fragments of the beta2 subunit. The first structure, consisting of the plexin-semaphorin-integrin domain, hybrid, integrin-epidermal growth factor 1 (I-EGF1), and I-EGF2 domains (PHE2), showed an L-shaped conformation with the bend located between the I-EGF1 and I-EGF2 domains. The second structure, which includes, in addition, the I-EGF3 domain, showed an extended conformation. The major reorientation of I-EGF2 with respect to the other domains in the two structures is accompanied by a change of torsion angle of the disulfide bond between Cys(461)-Cys(492) by 180 degrees and the conversion of a short alpha-helix (residues Ser(468)-Cys(475)) into a flexible coil. Based on the PHE2 structure, we introduced a disulfide bond between the plexin-semaphorin-integrin domain and I-EGF2 domains in the beta2 subunit. The resultant alphaLbeta2 integrin (leukocyte function-associated antigen-1) variant was locked in a bent state and could not be detected with the monoclonal antibody KIM127 in Mg(2+)/EGTA. However, it retained the binding activity to ICAM-1. These results provide a structural hypothesis for our understanding of the transition between the resting and active states of leukocyte function-associated antigen-1.
A structural hypothesis for the transition between bent and extended conformations of the leukocyte beta2 integrins.,Shi M, Foo SY, Tan SM, Mitchell EP, Law SK, Lescar J J Biol Chem. 2007 Oct 12;282(41):30198-206. Epub 2007 Aug 1. PMID:17673459[13]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Ohashi Y, Yambe T, Tsuchiya S, Kikuchi H, Konno T. Familial genetic defect in a case of leukocyte adhesion deficiency. Hum Mutat. 1993;2(6):458-67. PMID:7509236 doi:http://dx.doi.org/10.1002/humu.1380020606
- ↑ Nelson C, Rabb H, Arnaout MA. Genetic cause of leukocyte adhesion molecule deficiency. Abnormal splicing and a missense mutation in a conserved region of CD18 impair cell surface expression of beta 2 integrins. J Biol Chem. 1992 Feb 15;267(5):3351-7. PMID:1346613
- ↑ Arnaout MA, Dana N, Gupta SK, Tenen DG, Fathallah DM. Point mutations impairing cell surface expression of the common beta subunit (CD18) in a patient with leukocyte adhesion molecule (Leu-CAM) deficiency. J Clin Invest. 1990 Mar;85(3):977-81. PMID:1968911 doi:http://dx.doi.org/10.1172/JCI114529
- ↑ Wardlaw AJ, Hibbs ML, Stacker SA, Springer TA. Distinct mutations in two patients with leukocyte adhesion deficiency and their functional correlates. J Exp Med. 1990 Jul 1;172(1):335-45. PMID:1694220
- ↑ Matsuura S, Kishi F, Tsukahara M, Nunoi H, Matsuda I, Kobayashi K, Kajii T. Leukocyte adhesion deficiency: identification of novel mutations in two Japanese patients with a severe form. Biochem Biophys Res Commun. 1992 May 15;184(3):1460-7. PMID:1590804
- ↑ Corbi AL, Vara A, Ursa A, Garcia Rodriguez MC, Fontan G, Sanchez-Madrid F. Molecular basis for a severe case of leukocyte adhesion deficiency. Eur J Immunol. 1992 Jul;22(7):1877-81. PMID:1352501 doi:http://dx.doi.org/10.1002/eji.1830220730
- ↑ Back AL, Kwok WW, Hickstein DD. Identification of two molecular defects in a child with leukocyte adherence deficiency. J Biol Chem. 1992 Mar 15;267(8):5482-7. PMID:1347532
- ↑ Back AL, Kerkering M, Baker D, Bauer TR, Embree LJ, Hickstein DD. A point mutation associated with leukocyte adhesion deficiency type 1 of moderate severity. Biochem Biophys Res Commun. 1993 Jun 30;193(3):912-8. PMID:7686755 doi:http://dx.doi.org/10.1006/bbrc.1993.1712
- ↑ Hogg N, Stewart MP, Scarth SL, Newton R, Shaw JM, Law SK, Klein N. A novel leukocyte adhesion deficiency caused by expressed but nonfunctional beta2 integrins Mac-1 and LFA-1. J Clin Invest. 1999 Jan;103(1):97-106. PMID:9884339 doi:10.1172/JCI3312
- ↑ Li L, Jin YY, Cao RM, Chen TX. A novel point mutation in CD18 causing leukocyte adhesion deficiency in a Chinese patient. Chin Med J (Engl). 2010 May 20;123(10):1278-82. PMID:20529581
- ↑ Parvaneh N, Mamishi S, Rezaei A, Rezaei N, Tamizifar B, Parvaneh L, Sherkat R, Ghalehbaghi B, Kashef S, Chavoshzadeh Z, Isaeian A, Ashrafi F, Aghamohammadi A. Characterization of 11 new cases of leukocyte adhesion deficiency type 1 with seven novel mutations in the ITGB2 gene. J Clin Immunol. 2010 Sep;30(5):756-60. doi: 10.1007/s10875-010-9433-2. Epub 2010 , Jun 12. PMID:20549317 doi:10.1007/s10875-010-9433-2
- ↑ Xu J, Gao XP, Ramchandran R, Zhao YY, Vogel SM, Malik AB. Nonmuscle myosin light-chain kinase mediates neutrophil transmigration in sepsis-induced lung inflammation by activating beta2 integrins. Nat Immunol. 2008 Aug;9(8):880-6. doi: 10.1038/ni.1628. Epub 2008 Jun 29. PMID:18587400 doi:10.1038/ni.1628
- ↑ Shi M, Foo SY, Tan SM, Mitchell EP, Law SK, Lescar J. A structural hypothesis for the transition between bent and extended conformations of the leukocyte beta2 integrins. J Biol Chem. 2007 Oct 12;282(41):30198-206. Epub 2007 Aug 1. PMID:17673459 doi:10.1074/jbc.M701670200
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