The human α2(XI) collagen (COL11A2) chain. Molecular cloning of cDNA and genomic DNA reveals characteristics of a fibrillar collagen with differences in genomic organization

Abstract

We have isolated three overlapping cDNA clones encoding the proα2(XI) collagen chain from a human chondrocyte cDNA library. Together, the cDNAs code for 257 uninterrupted Gly-X-Y triplets (almost 80% of the triple helical domain) and about 200 amino acid residues of the carboxyl telopeptide and carboxyl propeptide. The identification of the clones as proα2(XI) cDNAs was based on the complete identity between the amino acid sequences of three tryptic peptides derived from human α2(XI) collagen and the cDNA-derived sequence. We have also sequenced six exons within a human genomic α2(XI) cosmid clone. This sequence shows that although type XI collagen belongs to the fibril-forming class of collagens, there are substantial differences in exon sizes at the 3' end of the gene when comparing the α2(XI) gene with those of human types I, II, and III collagens. Finally, proα2(XI) cDNA has been used as a probe to determine the location of the gene by in situ hybridization of chromosome spreads. The results demonstrate that the gene is located close to the region p212 on chromosome 6. Northern blot analysis shows that the gene is expressed in cartilage but not in adult liver, skin, and tendon.