Structure of the Human Type XIX Collagen (COL19A1) Gene, Which Suggests It Has Arisen from an Ancestor Gene of the FACIT Family

Abstract

Type XIX collagen is a newly discovered member of the FACIT (fibril-associated collagens with interrupted triple helices) group of extracellular matrix proteins. Based on the primary structure, type XIX collagen is thought to act as a cross-bridge between fibrils and other extracellular matrix molecules. Here we describe the complete exon/intron organization ofCOL19A1and show that it contains 51 exons, spanning more than 250 kb of genomic DNA. The comparison of exon structures ofCOL19A1and 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 α1(XIX) chain is similar to that of the NC 1–COL 1–NC 2–COL 3–NC 3 domain of the α2(IX) chain except for the NC 3 domain of α1(XIX). The exons encoding the COL 5–NC 6 domain of α1(XIX) are also similar to those of the COL 3–NC 4 domain of α1(IX) chain. Previously,COL19A1was mapped to human chromosome 6q12–q14, whereCOL9A1is also located. Likewise, the present work shows that the mouseCol19a1gene is located on mouse chromosome 1, region A3, whereCol9a1has also been mapped. Taken together, the data suggest thatCOL19A1andCOL9A1(Col19a1andCol9a1) were duplicated from the same ancestor gene of the FACIT family. Three CA repeat markers with high heterozygosity were found inCOL19A1.These markers may be useful for linkage analysis of age-related inheritable diseases involved in eyes and/or brain.