Cloning of alpha 1(IV) and alpha 2(IV) collagen cDNAs from rabbit corneal endothelial cell RNA.

To understand the role of type IV collagen in embryogenesis, regeneration, and tissue repair of the cornea at the molecular level, the authors isolated clones coding for rabbit alpha 1(IV) and alpha 2(IV) chains from a cDNA library constructed with rabbit corneal endothelial cell RNA. The isolated alpha 2(IV) cDNA clones encode a part of a 5' untranslated region, the signal peptide, the 7S domain, part of the triple-helical domain, and the entire carboxyl-terminal nontriple-helical (NC1) domain. By cross hybridization, using one of the alpha 2(IV) cDNA inserts, a cDNA clone encoding the alpha 1(IV) chain was isolated from a lambda gt10 library primed with oligo(dT). The clone covered a short portion of the triple-helical domain, the entire NC1 domain, and a short 3' untranslated region. The nucleotide-sequence analysis of these clones provides, for the first time to the authors' knowledge, the primary structure of the carboxyl-terminal portion of both rabbit alpha 1(IV) and alpha 2(IV) collagen chains. Between the alpha 1(IV)NC1 and the alpha 2(IV)NC1, 61% and 66% sequence similarities were observed at the amino acid and nucleotide levels, respectively. The locations of all the 12 cysteinyl residues were conserved in the two NC1 sequences.