Z-DNA-forming sequences at a putative duplication site in the human annexin VI-encoding gene.

We report here the presence of five stretches of alternating purine/pyrimidine (APP) intronic sequence close to the 5' end of the first exon in the C-terminal half of the human annexin VI-encoding gene (ANX VI). ANX VI, which comprises eight conserved repeats, is considered to have arisen by duplication of a hypothetical four repeat Anx; the location of the duplication would be predicted to occur within the intron where the APP sequences have been identified. The APP sequences have, by computer prediction, been identified as having significant potential to form Z-DNA. We discuss the significance of these potential Z-DNA-forming sequences being located in a region predicted to be the site of duplication which gave rise to the human ANX VI gene.