M6P/IGF2R imprinting evolution in mammals

Mol Cell. 2000 Apr;5(4):707-16. doi: 10.1016/s1097-2765(00)80249-x.


Imprinted gene identification in animals has been limited to eutherian mammals, suggesting a significant role for intrauterine fetal development in the evolution of imprinting. We report herein that M6P/IGF2R is not imprinted in monotremes and does not encode for a receptor that binds IGF2. In contrast, M6P/IGF2R is imprinted in a didelphid marsupial, the opossum, but it strikingly lacks the differentially methylated CpG island in intron 2 postulated to be involved in imprint control. Thus, invasive placentation and gestational fetal growth are not required for imprinted genes to evolve. Unless there was convergent evolution of M6P/ IGF2R imprinting and receptor IGF2 binding in marsupials and eutherians, our results also demonstrate that these two functions evolved in a mammalian clade exclusive of monotremes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Biological Evolution*
  • Carrier Proteins / genetics*
  • DNA, Complementary / genetics
  • Echidna / genetics
  • Genomic Imprinting*
  • Insulin-Like Growth Factor II / metabolism*
  • Introns
  • Male
  • Mammals / genetics*
  • Molecular Sequence Data
  • Opossums / genetics
  • Platypus / genetics
  • Receptor, IGF Type 2 / genetics*
  • Sequence Alignment
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid


  • Carrier Proteins
  • DNA, Complementary
  • Receptor, IGF Type 2
  • Insulin-Like Growth Factor II

Associated data

  • GENBANK/AF151171
  • GENBANK/AF151172
  • GENBANK/AF151173
  • GENBANK/AF225876
  • GENBANK/AF225877
  • GENBANK/AF225894
  • GENBANK/AF225895