Human decorin gene: intron-exon junctions and chromosomal localization.

All of the protein-encoding exons and the 3' flanking region of the human decorin gene have been cloned and partially sequenced. The locations of the intron-exon junctions within the coding portion of the gene were identical to those found for the homologous human gene, biglycan. The sizes of the introns in the decorin gene, however, were substantially larger than those of the same introns of the biglycan gene. Portions of introns 1, 2, and 3 as well as exon 1 were not found during our extensive screening process. The 5' end of intron 2 was found to have an AG-rich region followed immediately by a CT-rich region. Furthermore, the 5' end of intron 3 was very rich in thymidine, whereas the 3' end of intron 7 was rich in adenosine. Several cDNA clones constructed from cultured human bone cell mRNA were found to contain a different sequence at the 5' end compared to that previously published for mRNA from a human embryonic fibroblast cell line. We were also unable to find the alternate 3' flanking region of the previously published cDNA sequence. We have mapped the human decorin gene by in situ methods to chromosome 12q21.3.