Characterization of FIII/YY1, a Xenopus laevis conserved zinc-finger protein binding to the first exon of L1 and L14 ribosomal protein genes.

The cDNA coding for the Xenopus laevis homolog of the transcriptional activator/repressor protein delta/YY1 was isolated from a lambda gt11 oocyte cDNA library. The deduced aminoacid sequence shows that the four zinc fingers of the DNA binding domain are 99% conserved when compared to the mouse (delta) and 95% to the human (YY1) proteins, while differences are found in the N-terminal region. In particular, the long run of consecutive glycines and histidines of delta and YY1 is missing. The protein, named FIII/YY1, was overexpressed into Xenopus oocytes from the cDNA under direction of the L14 rp-promoter and found to share antigenic and DNA-binding properties with the oocyte endogenous protein binding to the first exon of the X.laevis ribosomal protein genes (rp-genes) L1 and L14.