Identification and characterization of amelogenin genes in monotremes, reptiles, and amphibians

Satoru Toyosawa, Colm O'Huigin, Felipe Figueroa, Herbert Tichy, Jan Klein

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Abstract

Two features make the tooth an excellent model in the study of evolutionary innovations: the relative simplicity of its structure and the fact that the major tooth-forming genes have been identified in eutherian mammals. To understand the nature of the innovation at the molecular level, it is necessary to identify the homologs of tooth-forming genes in other vertebrates. As a first step toward this goal, homologs of the eutherian amelogenin gene have been cloned and characterized in selected species of monotremes (platypus and echidna), reptiles (caiman), and amphibians (African clawed toad). Comparisons of the homologs reveal that the amelogenin gene evolves quickly in the repeat region, in which numerous insertions and deletions have obliterated any similarity among the genes, and slowly in other regions. The gene organization, the distribution of hydrophobic and hydrophilic segments in the encoded protein, and several other features have been conserved throughout the evolution of the tetrapod amelogenin gene. Clones corresponding to one locus only were found in caiman, whereas the clawed toad possesses at least two amelogenin-encoding loci.

Original languageEnglish (US)
Pages (from-to)13056-13061
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume95
Issue number22
DOIs
StatePublished - Oct 27 1998

All Science Journal Classification (ASJC) codes

  • General

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