The amelogenin genes encode abundant enamel proteins that are required
for the development of normal tooth enamel. These genes are active on
ly in enamel-forming ameloblasts within the dental organ of the develo
ping tooth, and are part of a small group of genes that are active on
both sex chromosomes. The upstream regions of the bovine X- and Y-chro
mosomal and the sole murine X-chromosomal amelogenin genes have been c
loned and sequenced, and conservation at nearly 60% is found in the 30
0 bp upstream of exon 1 for the 3 genes. A region of the bovine X-chro
mosomal gene that has inhibitory activity when assayed by gene transfe
r into heterologous cells includes motifs that have a silencing activi
ty in other genes, and may be important to the mechanism that represse
s amelogenin expression in non-ameloblast cells in vivo. A comparison
of sequences from three genes has led to the identification of several
regions with conserved motifs that are strong candidates for having p
ositive or negative regulatory functions, and these regions can now be
tested further for interaction with nuclear proteins, and for their a
bility to regulate expression in vivo. (C) 1998 Elsevier Science B.V.
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