Molecular cloning of chicken type VI collagen. Primary structure of the subunit alpha 2(VI)-pepsin

We have isolated a cDNA clone of 2160 base pairs that encodes the entire collagenous domain and large parts of the adjacent globular regions of the alpha 2 subunit of chicken type VI collagen. The collagenous domain shows one interruption in the repetitive Gly-X-Y sequence and comprises 335 amino acid residues. There are seven putative cell adhesion signals (Arg-Gly-Asp) present in this domain, as well as 1 cysteine residue which may be involved in the formation of type VI collagen dimers. The cDNA hybridizes specifically to a 4.2-kilobase pair mRNA abundant in chicken and human fibroblasts. Virally transformed fibroblasts contain drastically reduced levels of this mRNA, indicating that the synthesis of type VI collagen is blocked at the transcriptional level in transformed cells.