STRUCTURE OF THE HUMAN TYPE-XIX COLLAGEN (COL19A1) GENE, WHICH SUGGESTS IT HAS ARISEN FROM AN ANCESTOR GENE OF THE FACIT FAMILY

Type XIX collagen is a newly discovered member of the FACIT (fibril-as sociated collagens with interrupted triple helices) group of extracell ular matrix proteins. Based on the primary structure, type XIX collage n is thought to act as a cross-bridge between fibrils and other extrac ellular matrix molecules. Here we describe the complete exon/intron or ganization of COL19A1 and show that it contains 51 exons, spanning mor e than 250 kb of genomic DNA. The comparison of exon structures of COL 19A1 and other FACIT family genes revealed several similarities among these genes. The structure of exons encoding the noncollagenous (NC) 1 -collagenous (COL) 1-NC 2-COL 2-NC 3-COL 3-NC 4 domain of the alpha 1( XIX) chain is similar to that of the NC 1-COL 1-NC 2-COL 3-NC 3 domain of the alpha 2(IX) chain except for the NC 3 domain of alpha 1(XIX). The exons encoding the COL 5-NC 6 domain of alpha 1(XIX) are also simi lar to those of the COL 3-NC 4 domain of alpha 1(IX) chain. Previously , COL19A1 was mapped to human chromosome 6q12-q14, where COL9A1 is als o located. Likewise, the present work shows that the mouse Col19a1 gen e is located on mouse chromosome 1, region A3, where Col9a1 has also b een mapped. Taken together, the data suggest that COL19A1 and COL9A1 ( Col19a1 and Col9a1) were duplicated from the same ancestor gene of the FACIT family. Three CA repeat markers with high heterozygosity were f ound in COL19A1. These markers may be useful for linkage analysis of a ge-related inheritable diseases involved in eyes and/or brain. (C) 199 7 Academic Press.