Duplicate leader exons in the mouse liver-type alkaline phosphatase gene

A mouse genomic region corresponding to that containing the E2 exon of the rat liver alkaline phosphatase gene was isolated and characterized. A sequence comparison of these two regions showed homology of about 85% and complete conservation of sequence stretchs around the splicing-donor site. This sequence was proved to be transcribed in the mouse liver as poly(A)+RNA. These data suggest that, together with the E1-type transcript, the mouse liver-type alkaline phosphatase gene is provided with at least two alternative leader exons.