cDNA cloning and developmental expression of cellular nucleic acid-bindingprotein (CNBP) gene in Xenopus laevis

The cloning and sequencing of a cDNA corresponding to one of the two Xenopu s cellular nucleic acid binding pi protein (CNBP) genes are presented. Comp arison of this cDNA sequence (xCNBP2) with the other previously reported (x CNBP1) reveals that, while the cDNA sequences are somewhat divergent, the a mino acid sequences are mostly unchanged. It has been determined that both gene copies can generate a shorter transcript, likely due to alternative sp licing, as previously demonstrated in human cells. The comparison of the cD NA sequences of Xenopus and of other species shows that the missing cDNA tr act of Xenopus does not coincide with the others, consistent with the utili zation of different splicing donor sires. The two gene copies are expressed at comparable levels, since the two corresponding mRNAs are similarly repr esented both in oocyte and embryo poly(A)(+) RNA. However, the shorter CNBP transcripts are slightly less represented than the longer CNBP transcripts , in both the oocyte and embryo. CNBP mRNA accumulation during development decreases before the mid-blastula stage and increases again thereafter. The polysome association of CNBP mRNA and the binding activity of CNBP to its target sequence of ribosomal protein mRNA 5'UTR have been analysed during d evelopment. (C) 2000 Elsevier Science B.V. All rights reserved.