key: cord-0042439-loxdgwo9
authors: Isacke, Clare M.; Horton, Michael A.
title: CEACAM family: Carcinoembryonic antigen cell adhesion family, CD66 family, C-CAM family
date: 2007-09-02
journal: The Adhesion Molecule FactsBook
DOI: 10.1016/b978-012356505-1/50031-9
sha: 9088a0b8a1be20be6e033c82d406cf1445255fd9
doc_id: 42439
cord_uid: loxdgwo9

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Thc human CEA family is part of a cluster of at lcast 28 genes divided into two functional groups. Ry genomic mapping, the CEACAM suhgroup contains seven mcmbcrs and the PSG (pregnancy-specific glycoprotc~nl subgroup of secreted molecules contains 11 memhers. The remaining genes arc thought to he pseudogenesf. Within thc hcst charactcrizcd CEACAM members, CEACAMl and CEACAM3 cncodc type 1 transmembranc proteins while CEACAM8, CEACAMh and CEA arc GPI anchored in the membrane. All mcmhcrs possess an N-terminal V-type Ig d o m a~n followed by bctwcen 0 and h C2-type Ig doma~ns. Apart from CEACAM3, the extracellular domains are extensively N-glycosylatcd. CEACAMl and CEACAMd have putative tyrosine phosphorylation sites in their cytoplasmic domains, which could bind signalling components such as the tyrosine phosphatases SI-IP-1 and SHP-2; CEACAMl can associate with the cytoplasmic tyrosine kinases Src, Lyn and Hck7v4. Alternative splicing results in CEACAMI, 3 and 7 isoforms with varying numbers of Ig domains and/or shorter cytoplasmic domains'. Further structural and sequence information on other CEACAM family memhers and memhers of the PSG family can be found in refs 1 and 2.

The CEACAM family can mediate homophilic cell-cell adhesion and in certain combinations, hcterophilic interactions with other family memhers". Rinding is via the V-type domain6.'. In addition, CEACAMI and CEACAM6 have been reported to bind E-selectin, CEACAMl and CEACAM3 can act as a receptors for Neisserin ~onorrhoeae and Neisseria meningitidisR, murine CEACAMl and CEACAM2 arc receptors for murine coronaviruses9, and CEACAMh can bind galectins.

Rind~n,q ;Issays indicatc a rolc for CEACAM family mcinhcrs in mctlinting ailhccion hctwccn granulocytes antilor hctwccn ~ranulocvtcs and epithelial cclls, ;lnd ;IS rnicrohi;ll rcccptors. In addition, signalling via CEACAMI 2nd CEACAM3 cytoplasmic dc~inains-I rnny rcgulatc the adhcsivc ;ictivity of the p, intcgrinsln and the cytolytic tunction of intracpithclial l y i~~p l~o c y t e~'~.

Diffcrcnt splice v;~ri:~nts of CEACAMI :~n d . i display different hactcrial trrlpism anrl invrlsionJ. I~ilportnntlv, mcmhcrs of thc CEACAM family arc strongly rlown-rc~~ilatcrl In ~nalisnancics, implicating thcsc receptors rls p~it;~tivc tuniour suppressors4. It should he noted that Cell-CAM 105 originally identifier1 in mts nnd tlcscrihcd ns n honiophilic adhesion molcculc involved in the fortnation and rnaintcnancc of hcpatocytc prllariz;ltion nnd cxhihi ting ecto-ATPnsc activity12J7, is CEACAM 1.

CEACAMI and CEACAM6 Arc abundant on granulocytes r~ntl cpithclinl cclls, CEACAMK 2nd CEACAM.3 arc restricted to ~ranulocvtcs, s n~l CEA is mostly found on cpithclinl cclls. In CEA thv C-tcrininus is protcolyticnlly clcnvcrl and n GPl anchor attechcd. H~IVCVCT, t l~c site of clc;~vagc has not hccn unarnhigouslv cictcrm~ncd. The sequences sequences underlined and in italics are cleaved off to form maturc CEACAM8 and a GPI anchor is added. 

Ig Family ohrink