PMC

A. Disease-unaffected peptides, collagen alpha-1(II) chain (ρ_Healthy = 0.451, p < 0.0001 and ρ_Diseased = 0.439, p < 0.0001) and collagen alpha-1(I) chain (ρ_Healthy = −0.224, p < 0.0001 and ρ_Diseased = −0.251, p < 0.0001). B. Disease-affected peptides, retinol-binding protein 4 (ρ_Healthy = 0.311, p < 0.0001 and ρ_Diseased = 0.149, p < 0.0001) and collagen alpha-1(I) chain (ρ_Healthy = −0.308, p < 0.0001 and ρ_Diseased = −0.045, p < 0.0001).

Cryptic RGD-containing peptides from collagen type I support cell adhesion. Peptides corresponding to the five different RGD-containing motifs of human collagen type I were synthesized with flanking cysteines and immobilized on non-tissue culture plates. The ability of stromal cells to attach to the peptides (A–D) or the ability of monoclonal antibodies to bind the immobilized peptides (E and F) was assessed. A, HUVEC adhesion to immobilized peptides. B, HMVEC adhesion to immobilized peptides. C, HRMVEC adhesion to immobilized peptides. D, human dermal fibroblast (HDF) adhesion to immobilized peptides. E, reactivity of mAb XL313 to immobilized peptides. F, reactivity of mAb XL166 to immobilized peptides. Data bars represent mean binding ± S.D. from at least three experiments each using triplicate wells. *, p < 0.05.

Previously published human markers are labelled A–G. All numbered peaks represent confirmed sequencing-matched peptides observed in human collagen (except E which is only known through similarity to homologous markers in other species).

Characterisation of binding sites for the DDR2–DDR1 hybrid protein DDR2-H3 on collagens II and III. Binding of recombinant DDR2-H3-Fc to immobilized collagen II Toolkit peptides (A) or collagen III Toolkit peptides (B) in a solid phase binding assay. Recombinant DDR2-H3-Fc protein was added at 10 μg/ml (110 nM) for 3 h at room temperature to 96 wells coated with collagen or peptides at 10 μg/ml. Bound protein was detected with anti-Fc antibodies and measured as absorbance at 492 nm. Shown are the mean +/− SD of four independent experiments, each performed in triplicates. CI: rat tail collagen I; CII: bovine collagen II; CIII: recombinant human collagen III; CIV: placental collagen IV; GPP and CRP peptides as in .