Cw. Gibson et al., DNA-SEQUENCES OF AMELOGENIN GENES PROVIDE CLUES TO REGULATION OF EXPRESSION, European journal of oral sciences, 106, 1998, pp. 292-298
The amelogenins are a heterogeneous group of enamel proteins, which ha
ve an important function in enamel formation, as mutations in the amel
ogenin gene result in the enamel defect amelogenesis imperfecta. The c
DNAs that encode murine, bovine, human, porcine, rat and opossum amelo
genins have been cloned, and as many as nine alternatively spliced mes
sages can be produced from a single primary transcript, explaining som
e of the protein heterogeneity. Bovine and human amelogenin genes are
found on both X and Y chromosomes, and the sexually dimorphic proteins
would have 87-93% identity. A comparison of genes from human, bovine
and mouse indicates that they are organized into seven exons, and sequ
ences are highly homologous among species. Bovine, murine and human up
stream regions also have similarities, with consensus sequences for po
tential binding of transcription factors, such as AP1 and CTF/NF1. Tra
nsgenic mouse studies have shown that 2300-3500 bp of upstream region
are sufficient for expression, while 900 bp are insufficient. Analysis
of DNA sequence has identified (a) major homology between species for
coding exons with the exception of exon 4, (b) similarities in upstre
am regions likely involved in tissue specific regulation of expression
, and (c) sequences at the RNA splice sites which may determine exon i
nclusion or skipping.