Cloning and analysis of the 5' portion of the human type-III procollagen gene (COL3A1)

We have isolated overlapping clones containing the 5'-terminal portion of the human pro-alpha 1(III) collagen gene (COL3A1). This has enabled us to extend our previous studies and thus generate a restriction map of nearly 64 kb of DNA encompassing all of COL3A1 and more than 20 kb of flanking sequences. Aside from the complete nucleotide and amino acid sequences of type-III N-pre-propeptide, this study has established the number of the corresponding exons, whose relative organization deviates from the pattern observed in the analogous regions of type-I procollagen genes, COL1A1 and COL1A2. Moreover, we have sequenced 1628 bp of the 5'-flanking region of COL3A1, from the transcription start point (tsp) to an AluI repetitive element. Pairwise comparison with the analogous segment of the mouse gene has showed 78% sequence similarity in nearly 270 bp immediately preceding the tsp and including the TATA element and a presumptive NF-1 binding site. Relatively close to the tsp, but upstream from the region of homology with the murine gene, a potential AP-1 binding site has also been identified.