FIGURE 1.

A, schematic diagram of recombinant bacterial collagen VCL-Int with the insertion of human α1(I) chain residues from Gly-496 to Pro-513 (red), including the integrin α2β1 binding sequence, GFPGER. Residue numbers are taken from the UniProt entry P02452, and numbering starts from the beginning of the triple helix region. Bacterial collagen residues (blue) are denoted by their position relative to the human sequence insertion G(−12)POG(−9)PRG(−6)EQG(−3)PQGARGERGFPGERGVQGPP. Underlined Gly residues are mutated to Ser individually. B, SDS-polyacrylamide gel showing all the recombinant proteins, including VCL-Int and the proteins with Gly replacements. The right lane contains the Novex Sharp protein standard (Invitrogen); collagen monomer chains run slower than expected as reported previously. C, MALDI-TOF spectrometry of VCL, VCL-Int, and a representative mutated protein (G505S). a.u., arbitrary units.