Allele-specific Structures in the Mouse Igf2-H19 Domain

Although most genes in the animal cell genome are expressed equally from the maternal and paternal alleles, a small number of specific loci are parentally imprinted. In the mouse, such sequences include the Igf2 (DeChiara et al. 1991) and Snrpn (Leff et al. 1992) genes, which are transcribed exclusively from the paternal allele, and Igf2r (Barlow et al. 1991) and H19 (Bartolomei et al. 1991), which are expressed from the maternal allele. The very existence of this phenomenon suggests that these sequences can be recognized in the gametes and marked in a manner that allows parental identity to be preserved during development. To learn more about the molecular mechanisms involved in distinguishing between the maternal and paternal alleles, we have concentrated on the region of mouse chromosome 7 containing both the Igf2 and H19 genes, sequences that are located within 90 kb of each other but are imprinted on opposite...