Atypical Gly-X-Y sequences surround interruptions in the repeating tripeptide pattern of basement membrane collagen.
The triple-helical domains of type IV collagen chains have more than 20 sites at which the repeating (Gly-X-Y)n pattern is interrupted. Analysis of alpha 1 (IV) and alpha 2 (IV) chains indicates the residues in the three Gly-X-Y triplets preceding or following interruptions differ statistically from the rest of the chain. Unusually high frequencies of charged residues are seen at a number of X and Y sites, with the charge density being particularly high C-terminal to the interruption site. Analyses were carried out on individual categories of interruptions, classified as insertions or deletions in the Y position. All of the residues in the X and Y positions of the triplets flanking insertion sites are atypical, with a high concentration of charged residues. Triplets flanking sites where there has been a deletion in the Y position show unusually high frequencies of charged residues at some sites, hydrophobic residues at other sites, and an invariant imino acid N-terminal to the interruption. The presence of atypical sequences surrounding interruptions could be important at a molecular level, related to triple-helix stability, or at a supramolecular level, related to the association of molecules to form networks in basement membranes.
Long
C G
CG
Department of Biochemistry, UMDNJ-Robert Wood Johnson Medical School, Piscataway 08854, USA.
Thomas
M
M
Brodsky
B
B
D000818:Animals; D001485:Basement Membrane / Q000378:metabolism; D003094:Collagen / Q000737:chemistry*; D014644:Genetic Variation; D006801:Humans; D051379:Mice; D009842:Oligopeptides / Q000737:chemistry*; D017354:Point Mutation; D011487:Protein Conformation; D017384:Sequence Deletion
D009842:Oligopeptides; D003094:Collagen