CLONING OF CDNA AND GENOMIC DNA ENCODING FIBROBLAST GROWTH-FACTOR RECEPTOR-4 OF XENOPUS-LAEVIS

We have isolated and characterized the cDNA and genomic DNA encoding f ibroblast growth factor receptor-4 of Xenopus laevis (XFGFR-4). The ge ne encompassing the total coding sequence spans about 10 kb, consists of 17 exons, and has an organization very similar to those of mammalia n genes encoding FGFR-1 and -2, except that the XFGFR-4 gene does not contain an alternative exon for the third immunoglobulin-like domain n or an internal poly(A)-addition site. Thus, XFGFR-4 appears not to gen erate multiple forms of mRNA, as are identified for the mammalian FGFR -1, -2 and -3 genes, The amino-acid sequence of XFGFR-4 shows high hom ology to other vertebrate FGFR-4 species, but the similarity was signi ficantly lower than in the cases of FGFR-1 and -2. Northern blot analy sis showed the XFGFR-4mRNA to occur throughout X. laevis,is early embr yogenesis in a profile different from those of X. laevis FGFR-1 and -2 .