Structure of mouse type IV collagen. Amino-acid sequence of the C-terminal 511-residue-long triple-helical segment of the alpha 2(IV) chain and its comparison with the alpha 1(IV) chain.

The sequence of 511 residues from the C-terminal portion of the triple helix of mouse alpha 2(IV) chain was determined by using the pepsin fragment P2 of collagen IV and two cDNA clones selected from an Engelbreth-Holm-Swarm (EHS) tumor library. The sequence contains nine interruptions of the triplet repeat Gly-Xaa-Yaa ranging in size from single insertions or deletions up to stretches of eleven amino acid residues. Five of these interruptions match those present in the homologous segment of the alpha 1(IV) chain but are otherwise different in length and/or sequence. A low homology was found for the triplet regions of the alpha 1(IV) and alpha 2(IV) chain which constitute more than 90% of the sequence. The data indicate a remote evolutionary relationship of the triple-helical sequences of the two constituent chains of basement membrane collagen.