THE HUMAN COL11A2 GENE STRUCTURE INDICATES THAT THE GENE HAS NOT EVOLVED WITH THE GENES FOR THE MAJOR FIBRILLAR COLLAGENS

The human COL11A2 gene was analyzed from two overlapping cosmid clones that were previously isolated in the course of searching the human ma jor histocompatibility region (Janatipour, M., Naumov, Y., Ando, A., S ugimura, K., Okamoto, N., Tsuji, K., Abe, K., and Inoko, H. (1992) Imm unogenetics 35, 272-278). Nucleotide sequencing defined over 28,000 ba se pairs of the gene. It was shown to contain 66 exons. As with most g enes for fibrillar collagens, the first intron was among the largest, and the introns at the 5'-end of the gene were in general larger than the introns at the 3'-end. Analysis of the exons coding for the major triple helical domain indicated that the gene structure had not evolve d with the genes for the major fibrillar collagens in that there were marked differences in the number of exons, the exon sizes, and codon u sage. The gene was located close to the gene for the retinoic X recept or beta in a head-to-tail arrangement similar to that previously seen with the two mouse genes (P. Vandenberg and D. J. Prockop, submitted f or publication). Also, there was marked interspecies homology in the i ntergenic sequences. The amino acid sequences and the pattern of charg ed amino acids in the major triple helix of the alpha 2(XI) chain sugg ested that the chain can be incorporated into the same molecule as alp ha 1(XI) and alpha 1(V) chains but not into the same molecule as the a lpha 3(XI)/alpha 1(II) chain. The structure of the carboxyl-terminal p ropeptide was similar to the carboxyl-terminal propeptides of the pro alpha 1(XI) chain and pro alpha chains of other fibrillar collagens, b ut it was shorter because of internal deletions of about 30 amino acid s.