Genomic organization of the extracellular coding region of the human FGFR4 and FLT4 genes: evolution of the genes encoding receptor tyrosine kinases with immunoglobulin-like domains.
Receptor tyrosine kinases with five, seven, and three Ig-like domains in their extracellular region are grouped in subclasses IIIa, IIIb, and IIIc, respectively. Here, we describe the genomic organization of the extracellular coding region of the human FGFR4 (IIIc) and FLT4 (IIIb) genes and compare it to that of the human FGFR1(IIIc), KIT, and FMS (IIIa). The results show that while genes belonging to the same subclass have an identical exon/intron structure in their extracellular coding region-as they do in their intracellular coding region-genes of related subclasses only have a similar exon/intron structure. These results strongly support the hypothesis that the genes of the three subclasses evolved from a common ancestor by duplications involving entire genes, already in pieces. Hypotheses on the origin of introns and on the difference in the number of extracellular Ig-like domains in the three gene subclasses are discussed.
Agnès
F
F
Laboratoire de Biochimie et Biologie Moléculaire, UPR41 CNRS, Faculté de Médecine, 2 Avenue du Professeur Léon Bernard, 35043 Rennes Cedex, France.
Toux
M M
MM
André
C
C
Galibert
F
F
D005091:Exons; D005110:Extracellular Space; D005796:Genes; D005803:Genes, Immunoglobulin; D006801:Humans; D007438:Introns; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D051499:Receptor, Fibroblast Growth Factor, Type 4; D011956:Receptors, Cell Surface / Q000235:genetics*; D017468:Receptors, Fibroblast Growth Factor / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D040321:Vascular Endothelial Growth Factor Receptor-3
D011956:Receptors, Cell Surface; D017468:Receptors, Fibroblast Growth Factor; C496371:FGFR4 protein, human; D020794:Receptor Protein-Tyrosine Kinases; D051499:Receptor, Fibroblast Growth Factor, Type 4; D040321:Vascular Endothelial Growth Factor Receptor-3