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The DNA sequence of two overlapping cDNA clones and a genomic lambda clone covering the region coding for 288 amino acids at the COOH terminus of the chicken type II procollagen gene is reported. This region consists of 4 exons coding for the last 15 amino acids of the triple helical domain and 273 amino acids which correspond to the COOH-terminal telopeptide and COOH-terminal propeptide. The sequence, base composition, and codon usage of this region of the type II procollagen gene show particularly high similarity to those of the chicken alpha 1(I) procollagen gene and differ from those of the alpha 2(I) and alpha 1(III) gene sequences. Two DNA tracts of low sequence similarity were observed. One of these regions spans the telopeptide and COOH-terminal propeptidase cleavage site, although 4-5 amino acids at the actual cleavage site are conserved compared with the alpha 1(I) and alpha 2(I) genes. A region of unusually high nucleotide sequence conservation is present in exon 2 (amino acids 171c - 186c ) consisting of approximately 45 nucleotides with only one or two base substitutions compared with the other procollagen genes. Within this conserved sequence is a site for carbohydrate attachment. The 3' nontranslated sequence of the type II procollagen mRNA is longer than that of either the alpha 1(I) or alpha 2(I) mRNA and contains several unusual long tracts consisting primarily of one or two bases. Although the canonical site for polyadenylation is not present, two related sequences, AACAAA and ATATAAA , are present 32 and 41 bases preceding the end of the major RNA species. The exon/intron structure of the type II procollagen gene is similar to that of other collagen genes which have been described. This DNA sequence provides the first extensive report of the amino acid sequence of chicken type II procollagen.

A segment of the type II procollagen gene has been isolated by screening a lambda Charon 4A library containing fragments of chicken genomic DNA. The specific clone, LgCOL(II), was selected by hybridization using overlapping inserts from two cDNA clones which are specific for a cartilage procollagen (Vuorio, E., Sandell, L., Kravis, D., Sheffield, V. C., Vuorio, T., Dorfman, A., and Upholt, W. B. (1982) Nucleic Acids Res. 10, 1175-1192). DNA sequence analysis of LgCOL(II) in the COOH-telopeptide region of the protein, shows conclusively that this DNA corresponds to the chicken type II procollagen gene. Hybridization of cDNA probes to restriction fragment gel blots together with DNA sequence analysis have established the orientation and position of the procollagen gene within the lambda Charon 4A vector and indicate that LgCOL(II) contains approximately 6 kilobase pairs of the type II procollagen gene plus additional DNA flanking the 3' end of the gene. DNA sequence analysis shows directly that LgCOL(II) contains DNA sequences identical with those in the cDNA clones. The portion of the gene from amino acid 578 of the triple helical region to the COOH-terminal end of the protein (approximately 700 amino acids) is contained within the clone, corresponding to approximately 50% of the amino acid coding sequence of the gene. This region of the chicken alpha 1 (type II) procollagen gene is encoded within a shorter segment of the chicken genome than is the corresponding region of the alpha 2(type I) procollagen gene.