View source for CD18

{{Lead too short|date=November 2016}}
{{Infobox gene}}
'''Integrin beta-2''' ('''CD18''') is a [[protein]] that in humans is encoded by the ''ITGB2'' [[gene]].

It is the beta subunit of four different structures: 
* [[LFA-1]] (paired with [[CD11a]])
* [[Macrophage-1 antigen]] (paired with [[CD11b]])
* [[Integrin alphaXbeta2]] (paired with [[CD11c]])
* [[Integrin alphaDbeta2]] (paired with [[CD11d]])

== Function ==
The ITGB2 protein product is the integrin beta chain beta 2. Integrins are integral cell-surface proteins composed of an alpha chain and a beta chain.  A given chain may combine with multiple partners resulting in different integrins.  For example, beta 2 combines with the alpha L chain to form the integrin LFA-1, and combines with the alpha M chain to form the integrin Mac-1. Integrins are known to participate in cell adhesion as well as cell-surface mediated signalling.<ref>{{cite web | title = Entrez Gene: ITGB2 integrin, beta 2 (complement component 3 receptor 3 and 4 subunit)| url = https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=3689| accessdate = }}</ref>

== Clinical significance==
In humans lack of CD18 causes [[Leukocyte Adhesion Deficiency]], a disease defined by a lack of leukocyte extravasation from blood into tissues. The beta 2 integrins have also been found in a soluble form.<ref>{{cite journal|last1=Gjelstrup|first1=L. C.|last2=Boesen|first2=T.|last3=Kragstrup|first3=T. W.|last4=Jorgensen|first4=A.|last5=Klein|first5=N. J.|last6=Thiel|first6=S.|last7=Deleuran|first7=B. W.|last8=Vorup-Jensen|first8=T.|title=Shedding of Large Functionally Active CD11/CD18 Integrin Complexes from Leukocyte Membranes during Synovial Inflammation Distinguishes Three Types of Arthritis through Differential Epitope Exposure|journal=The Journal of Immunology|date=8 September 2010|volume=185|issue=7|pages=4154–4168|doi=10.4049/jimmunol.1000952}}</ref> The soluble beta 2 integrins are ligand binding and plasma levels are inversely associated with disease activity in the autoimmune disease spondyloarthritis.<ref>{{cite journal|last1=Kragstrup|first1=Tue W|last2=Jalilian|first2=Babak|last3=Hvid|first3=Malene|last4=Kjærgaard|first4=Anders|last5=Østgård|first5=René|last6=Schiøttz-Christensen|first6=Berit|last7=Jurik|first7=Anne G|last8=Robinson|first8=William H|last9=Vorup-Jensen|first9=Thomas|last10=Deleuran|first10=Bent|title=Decreased plasma levels of soluble CD18 link leukocyte infiltration with disease activity in spondyloarthritis|journal=Arthritis Research & Therapy|date=2014|volume=16|issue=1|pages=R42|doi=10.1186/ar4471}}</ref>

== Interactions ==
CD18 has been shown to [[Protein-protein interaction|interact]] with:
{{div col|colwidth=20em}}
* [[FHL2]],<ref name = pmid10906324>{{cite journal | vauthors = Wixler V, Geerts D, Laplantine E, Westhoff D, Smyth N, Aumailley M, Sonnenberg A, Paulsson M | title = The LIM-only protein DRAL/FHL2 binds to the cytoplasmic domain of several alpha and beta integrin chains and is recruited to adhesion complexes | journal = The Journal of Biological Chemistry | volume = 275 | issue = 43 | pages = 33669–78 | date = October 2000 | pmid = 10906324 | doi = 10.1074/jbc.M002519200 }}</ref> 
* [[GNB2L1]],<ref name = pmid9442085>{{cite journal | vauthors = Liliental J, Chang DD | title = Rack1, a receptor for activated protein kinase C, interacts with integrin beta subunit | journal = The Journal of Biological Chemistry | volume = 273 | issue = 4 | pages = 2379–83 | date = Jan 1998 | pmid = 9442085 | doi =  10.1074/jbc.273.4.2379}}</ref>
* [[ICAM-1]],<ref name = pmid10352278>{{cite journal | vauthors = Kotovuori A, Pessa-Morikawa T, Kotovuori P, Nortamo P, Gahmberg CG | title = ICAM-2 and a peptide from its binding domain are efficient activators of leukocyte adhesion and integrin affinity | journal = Journal of Immunology | volume = 162 | issue = 11 | pages = 6613–20 | date = June 1999 | pmid = 10352278 | doi =  }}</ref><ref name = pmid11279101>{{cite journal | vauthors = Lu C, Takagi J, Springer TA | title = Association of the membrane proximal regions of the alpha and beta subunit cytoplasmic domains constrains an integrin in the inactive state | journal = The Journal of Biological Chemistry | volume = 276 | issue = 18 | pages = 14642–8 | date = May 2001 | pmid = 11279101 | doi = 10.1074/jbc.M100600200 }}</ref><ref name = pmid7642561>{{cite journal | vauthors = Huang C, Springer TA | title = A binding interface on the I domain of lymphocyte function-associated antigen-1 (LFA-1) required for specific interaction with intercellular adhesion molecule 1 (ICAM-1) | journal = The Journal of Biological Chemistry | volume = 270 | issue = 32 | pages = 19008–16 | date = August 1995 | pmid = 7642561 | doi =  10.1074/jbc.270.32.19008}}</ref>  and
* [[PSCD1]].<ref name = pmid9765275>{{cite journal | vauthors = Rietzler M, Bittner M, Kolanus W, Schuster A, Holzmann B | title = The human WD repeat protein WAIT-1 specifically interacts with the cytoplasmic tails of beta7-integrins | journal = The Journal of Biological Chemistry | volume = 273 | issue = 42 | pages = 27459–66 | date = October 1998 | pmid = 9765275 | doi =  10.1074/jbc.273.42.27459}}</ref><ref name = pmid10835351>{{cite journal | vauthors = Geiger C, Nagel W, Boehm T, van Kooyk Y, Figdor CG, Kremmer E, Hogg N, Zeitlmann L, Dierks H, Weber KS, Kolanus W | title = Cytohesin-1 regulates beta-2 integrin-mediated adhesion through both ARF-GEF function and interaction with LFA-1 | journal = The EMBO Journal | volume = 19 | issue = 11 | pages = 2525–36 | date = June 2000 | pmid = 10835351 | pmc = 212768 | doi = 10.1093/emboj/19.11.2525 }}</ref> 
{{Div col end}}

== See also ==
* [[leukocyte adhesion deficiency]]
* [[integrin]]

== References ==
{{reflist}}

== Further reading ==
{{refbegin | 2}}
* {{cite journal | vauthors = Bunting M, Harris ES, McIntyre TM, Prescott SM, Zimmerman GA | title = Leukocyte adhesion deficiency syndromes: adhesion and tethering defects involving beta 2 integrins and selectin ligands | journal = Current Opinion in Hematology | volume = 9 | issue = 1 | pages = 30–5 | date = Jan 2002 | pmid = 11753075 | doi = 10.1097/00062752-200201000-00006 }}
* {{cite journal | vauthors = Roos D, Law SK | title = Hematologically important mutations: leukocyte adhesion deficiency | journal = Blood Cells, Molecules & Diseases | volume = 27 | issue = 6 | pages = 1000–4 | year = 2003 | pmid = 11831866 | doi = 10.1006/bcmd.2001.0473 }}
* {{cite journal | vauthors = Gahmberg CG, Fagerholm S | title = Activation of leukocyte beta2-integrins | journal = Vox Sanguinis | volume = 83 Suppl 1 | issue =  | pages = 355–8 | date = August 2002 | pmid = 12617168 | doi = 10.1111/j.1423-0410.2002.tb05333.x }}
* {{cite journal | vauthors = Schymeinsky J, Mócsai A, Walzog B | title = Neutrophil activation via beta2 integrins (CD11/CD18): molecular mechanisms and clinical implications | journal = Thrombosis and Haemostasis | volume = 98 | issue = 2 | pages = 262–73 | date = August 2007 | pmid = 17721605 | doi = 10.1160/th07-02-0156 }}
{{refend}}
{{PDB Gallery|geneid=3689}}

== External links ==
* {{MeshName|CD18+antigen}}
*[http://cmkb.cellmigration.org/report.cgi?report=orth_overview&orth_acc=co00001789 ITGB2] Info with links in the [http://www.cellmigration.org/index.shtml Cell Migration Gateway]
* {{UCSC gene info|ITGB2}}

{{Clusters of differentiation}}
{{Clusters of differentiation by lineage}}
{{Complement system}}
{{Cell adhesion molecules}}
{{Integrins}}

{{Use dmy dates|date=April 2017}}

[[Category:Integrins]]
[[Category:Clusters of differentiation]]


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