Interaction of collagen with C1q via its collagen-like portion.

Interactions between human collagens type I, II and III with human C1q or its collagen-like fragment (CLF) were investigated with different techniques. It was found that in solution both C1q and CLF form stable complexes with the native collagens. No preferential binding to a specific collagen type was observed. If C1q (CLF) was adsorbed to polystyrene or fixed to erythrocytes, a more efficient interaction with collagen was displayed by C1q than by CLF. If collagen represents the solid phase, the binding of CLF is stronger than that of C1q. Inhibition studies indicate that the interaction between C1q and collagens takes place via the collagen-like part of C1q. Intermolecular attraction due to polar amino acid residues seems to be of major importance for this interaction.