Molecular cloning of cDNA for the ζ isoform of the 14-3-3 protein: Homologous sequences in the 3′-untranslated region of frog and human ζ isoforms

14-3-3 proteins constitute a family of well-conserved eukaryotic proteins that possess diverse biochemical activities such as regulation of gene transcription, cell proliferation and activation of protein kinase C. At least 7 subtypes (α to θ) of 14-3-3 protein are known, but the ζ subtype of this protein has been cloned only in mammals. We cloned the ζ subtype of 14-3-3 protein (14-3-3ζ) from the frog, Rana rugosa. The sequence encoded 245 amino acids that share 92% identity with rat and bovine 14-3-3ζs, and 92% with human phospholipase A2 (PLA2; 14-3-3ζ). Northern blot analysis revealed a single band of about 1.8 kb in tadpoles at stage 25. The 14-3-3ζ mRNA level was high in the brain, lung, spleen and kidney, and low in the heart and testis, as opposed to the mRNA level, which was only faintly detected in the liver, pancreas, ovary and muscle. Furthermore, high similarity in the 3′-untranslated region (3′-UTR) was observed between frog and human 14-3-3ζ cDNA. The results suggest that 14-3-3ζ is highly conserved throughout eukaryotic evolution, and that the homologous sequence in the 3′-UTR of 14-3-3ζ cDNA may be conserved in frogs and humans.