Sequences coding for the ribosomal protein L14 in Xenopus laevis and Xenopus tropicalis; homologies in the 5' untranslated region are shared with other r-protein mRNAs

In the haploid genome of Xenopus laevis there are two genes coding for the r-protein L14. It is not known if they are located on the same chromosome. cDNA clones deriving from the transcripts of the two genes have been isolated from an oocyte messenger cDNA bank showing that they are both expressed. We have studied the structure of one of the L14 genes by Electron Microscopy, restriction mapping and sequencing. An allelic form of the L14 gene was also isolated. It contains a large deletion covering the 5' end region up to the middle of the third intron. The 5' end of the X. laevis L14 gene was compared to that of the corresponding gene in the closely related species X. tropicalis and found to be highly conserved. The L14 gene has multiple initiation sites, but the large majority of the transcripts start in the middle of a pyrimidine tract not preceded by a canonical TATA box as in other eukaryotic housekeeping genes. The X. laevis L1 and L14 genes have a common decanucleotide in the first exon in the same position with regard to the initiator ATG which just precedes the first intron. The decanucleotide shows homology with the X. laevis 18S rRNA.