A schematic diagram of the interaction network of major fibrillar collagens showing the classes of molecules that interact with them, together with representative examples of each class (plotted with Cytoscape 3.2.1, based on multiple sources including MatrixDB [http://matrixdb.ibcp.fr/]). A gray outline around the molecule name indicates the crystal structure of the molecule has been determined. Molecules connected to collagen by solid lines indicate that the structures of cocrystals of that molecule (or part of that molecule) with a collagen-like peptide have been solved. BMP, bone morphogenetic protein; BSP, bone sialoprotein; DDR, discoidin domain receptor; GAG, glycoaminoglycan; GPVI, glycoprotein VI; HSP, heat shock protein; HYAL, hyaluronidase; LAIR-1, leukocyte-associated immunoglobulin-like receptor-1; LOX, lysyl oxidase; LRC, leukocyte receptor complex; MMP, matrix metalloproteinase; PCPE, procollagen C-proteinase enhancer; PDGF, platelet-derived grwoth factor; PEDF, pigment epithelium-derived factor; PG, proteoglycan; SPARC, secreted protein acidic and rich in cysteine; THBS, thrombospondins; VWF, von Willebrand factor. The central electron micrograph of collagen fibrils is from Gross and Schmitt.²