Ig superfamily
Ig superfamily members are known to mediate cell adhesion, as:
NCAM1 (MIM.116930)
ICAM1 (MIM.147840)
VCAM1 (vascular cell adhesion molecule-1) (MIM.192225)
They also mediate antigen recognition:
immunoglobulins (IGH, IGL, IGK)
T-cell receptors (TCRA, TCRB, TCRD, TCRG)
MHC molecules.
In addition, a subgroup comprising 30 members characterized by the presence of one or more immunoreceptor tyrosine-based inhibitory motifs (ITIMs) within their cytoplasmic domain has also been recognized. PECAM1, which has 6 ITIMs within its cytoplasmic domain, is a member of this subfamily;
Another subfamily is the carcinoembryonic antigen gene family (CEA gene family).