Promoter proximal intron-exon structure of the vWF gene across vertebrate species. Shown in order are the first exon (5′UTR), first intron, second exon (which begins with the ATG translation initiation codon), second intron, third exon, and part of the third intron in multiple species. In the case of the rat gene, there is no information about the genomic sequence upstream of the translation start site. Thus, the presence of an upstream first exon containing the 5′UTR (box with dashed outline) and a first intron (dashed line) can only be inferred from their conserved arrangement in higher and lower species.