Xenopus homeobox-containing cDNAs expressed in early development.

We report the isolation of six different homeobox-containing genes in Xenopus laevis which are expressed during early embryogenesis. cDNA clones of all of them were partially sequenced including two from previously isolated Xenopus genomic loci and found to contain homeodomains which share a high degree of homology with the Antennapedia protein (50 to 59 out of 60 amino acids). We find a short region of homology (consensus Ile Tyr Pro Trp Met) in four of the cDNAs, which is also present in Antennapedia and that may correspond to a bend region preceding the homeodomain. Northern blots have been performed to show the transcriptional pattern through early frog embryogenesis. Three of the genes are expressed only during a very narrow period of embryogenesis, reinforcing the view that homeobox genes are developmentally regulated.