ABSTRACT
The carcinoembryonic antigen (CEA) gene family consists of 29 separate genes which are located within the long arm of chromosome 19. The isolation of cDNAs or genes for CEA family members led to their identification in 1986 as members of the immunoglobulin (Ig) supergene family (review: Thompson and Zimmermann, 1988; Thompson et al., 1987 ; Thompson et al., 1991). All CEA family members are glycoproteins composed of a N-terminal Ig variable region-like domain, followed by 0,2,3,4, or 6 Ig constant region-like domains of subtype A or B, and terminated by a processed hydrophobic C-terminal domain. The CEA family may be subdivided into two groups based on sequence comparisons. The first is CEA and the CEA crossreacting molecules, including nonspecific cross-reacting antigen (NCA), biliary glycoprotein (BGP) and CGM-6. The second consists of the pregnancy-specific glycoproteins. The CEA subgroup is subdivided further by structural characteristics into those members attached to the outer cell membrane by glycophosphatidyl inositol (CEA, NCA, CGM-6), and those that have both transmembrane and cytoplasmic domains (BGP splice variants).
