title: Homologies between the non-collagenous C-terminal (NC1) globular domains of the alpha 1 and alpha 2 subunits of type-IV collagen.
abstract: The non-collagenous C-terminal globular domain (NC1) of type-IV collagen has the dual role of initiating triple-helix formation among the subunits and of crosslinking two collagen molecules during basement-membrane meshwork formation. By cloning a cDNA for the NC1 domain of the alpha 2(IV) collagen chain, we have found a high degree of homology (63% for nucleotides, 66% for amino acids) between the NC1 of the alpha 2 and alpha 1 chains of type-IV collagen. All cysteine residues are conserved. This high degree of homology is not found within the helical portion where the homology is 41% for amino acids (only 14% if the obligatory glycine is not used for this analysis). We propose that this high degree of homology within the non-collagenous domain indicates a close evolutionary relationship maintained by functional restraints between the two chains of type IV collagen.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D003094:Collagen / Q000145:classification / Q000235:genetics*; D003545:Cysteine / Q000235:genetics; D004247:DNA / Q000235:genetics; D051379:Mice; D011487:Protein Conformation
chemical_list: D003094:Collagen; D004247:DNA; D003545:Cysteine