Structure of the human type IV collagenase gene

The structure of the gene for human 70-kDa type IV collagenase (gelatinase) was determined. Three overlapping genomic clones were isolated and shown to contain 0.4 kilobase (kb) of the 5'-flanking region, the 27-kb structural gene, and 4.5 kb of the 3'-flanking region. The gene has 13 exons that vary in length from 110 to 901 base pairs (bp) and 12 introns that range from 175 to 4350 bp. Alignment of intron locations demonstrated that introns 1-4 and 8-12 of the type IV collagenase gene coincide with intron locations in the interstitial collagenase and stromelysin genes, indicating a close structural relationship of these metalloproteinase genes. Exons 5-7 are each 174 bp in size, and each codes for one complete internal repeat that resembles the collagen-binding domains of fibronectin. The transcription initiation site was determined by primer extension and S1 nuclease analyses. Analysis of the 0.4-kb 5'-flanking region of the gene showed that, in contrast to the genes of interstitial collagenease and stromelysin, there is no TATA box or 12-O-tetradecanoylphorbol-13-acetate-responsive element present in the promoter region, whereas there are two GC boxes. There is no CAAT box, but a potential binding site (CCCCAGGC) for the transcription factor AP-2 is located in the first exon.