COMPARISON OF UPSTREAM REGIONS OF X-CHROMOSOMAL AND Y-CHROMOSOMAL AMELOGENIN GENES

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. All rights reserved.