CHARACTERIZATION OF 2 GENES-CODING FOR A SIMILAR 4-CYSTEINE MOTIF OF THE AMINO-TERMINAL PROPEPTIDE OF A SEA-URCHIN FIBRILLAR COLLAGEN

We report the characterization of the 5' region of the gene coding for the 2 alpha fibrillar collagen chain of the sea urchin Paracentrotus lividus. This sequence analysis identified the intron/exon organizatio n of the region of the gene coding for the signal peptide, the cystein e-rich domain and the 12 repeats of the four-cysteine module of the un usually long amino-propeptide. This still unknown four-cysteine motif is generally encoded by one exon, which confirms that the distinct ami no-propeptide structures of the fibril lar collagens arise from the sh uffling of several exon-encoding modules. Moreover, Southern blot anal ysis of the sea urchin genome and sequencing of selected genomic clone s allowed us to demonstrate that several sea urchin genes could potent ially code for the four-cysteine module. Curiously, one of these genes lacks the exons coding for four repeats of this motif while, in anoth er gene, the same exons are submitted to an alternative splicing event .