Fig. 4

Domain organization of CEACAM proteins in primates. The domain organization of CEACAM family members from selected primates was predicted by gene analysis. Human and rhesus monkey PSG domain organizations were confirmed by EST sequences. Domains are shown in light colors for rhesus monkey PSGs not found in the EST database. Their domain composition is deduced from genomic analyses. If more than one splice variant exists, the longest is shown. The orthologous CEACAM family members are conserved and counterparts can be assigned between primate species. CEACAM1-related members represent paralogs and are much more variable between primate species. IgV-like domains are shown as red, IgC-like domains as blue ovals with subtypes A and B shown in darker and lighter coloration, respectively. Numbers in the IgC-like domains identify their origin from the first or second A, B exon pair in the PSG gene. Note that in human PSGs B1 exons are never spliced-in due to a splice acceptor defect in most PSG genes except in PSG11. In rhesus monkey such splice events are observed (PSG9, PSG17). The predicted signaling motifs in the cytoplasmic domains are schematically shown as green (ITAM), blue (ITAM-like motif), red (ITIM) and yellow boxes (ITSM). Transmembrane domains and GPI anchors are indicated by black and green lines, respectively. Note the highly variable number of PSG in the different primate species (between 0 and 21). Identical PSG numbering does not imply orthologous relationship. Also note the lack of CEACAMs with ITAM-like motifs in NWM and their expansion in tarsius and mouse lemur. For the bush baby the domain organization could not be delineated for all CEACAM1-like proteins due to low quality of the genome assembly. C, CEACAM; P, PSG