Structure of the mRNA and of the gene coding for the rabbit erythroid 15-lipoxygenase

Abstract

The complete structure of the rabbit erythroid cell-specific 15-lipoxygenase mRNA and its gene was established by sequencing cDNA and genomic recombinants. The transcription initiation site was obtained by primer-extension sequencing. A presumptive promoter structure was characterized by sequencing 0.5 kb 5' to the transcription initiation site and by transfection experiments using constructs with the chloramphenicol transferase gene. The mRNA codes for a polypeptide of 662 amino acids. Its 3' untranslated region contains an intriguing repeated sequence of 10 copies with the consensus C4PuC3TCTTC4AAG which may be involved in its regulation during reticulocyte maturation. The transcription unit consists of 8.0 kb and is split like the gene for the leukocyte 5' lipoxygenase by 13 introns. Another interesting aspect in the structure of the 15-LOX gene is a highly conserved repeat in intron seven consisting of a unit of 54 nucleotides which is repeated eight times. Comparing the predicted amino acid sequence with those from other lipoxygenases published recently shows that lipoxygenases are a related group of enzymes which may have arisen from a common ancestral gene.