Fig. 1

Chromosomal arrangement of ceacam genes in X. tropicalis and X. laevis. Arrowheads represent genes with their transcriptional orientation. Xenopus ceacam gene clusters are subdivided in group 1 (yellow) and group 2 members (blue). For X. laevis two homeologous ceacam clusters are found on chromosome 7 L and 7S which were generated by hybridization during speciation. Homeologs are indicated by L and S. Human CEACAM1-related genes are indicated in yellow, when predominantly expressed in trophoblast cells in red; the CEACAM genes for which orthologs can be identified in mammals are shown in blue and marker genes in black. Their syntenic relationship is shown by blue lines. Names of CEACAM1-like genes with ITIM-encoding exons are shown in red and with ITAM and ITAM-like motif-encoding exons in green and blue, respectively. Red double arrows symbolize potential recombination events between regions with ceacam genes containing ITIM or ITAM/ITAM-like motifs (genes shown in red boxes). Note that, in general, the genes in the same subcluster show the same, in different subclusters opposite transcriptional orientation. The nucleotide numbering of the chromosomes starts at the telomere of the short arms located to the left. The databases and the versions used are indicated below the species name. c, ceacam, C, CEACAM; chr, chromosome; P, pregnancy-specific glycoprotein (PSG) genes