The Structural Analogy of MASP-2 with Thrombin and MASP-1 Reveals Strong Binding with PAR4

The historical discovery that thrombin activates Protease-Activated Receptor 4 (PAR4) has paved the way for several novel findings. Besides thrombin, the complement lectin pathway protease Mannose-Binding Lectin-Associated Serine Protease-1 (MASP-1) also binds to PAR4, albeit with lower affinity. Similar to thrombin, MASP-1 activates Ca²⁺ signaling pathways in endothelial cells. MASP-2, a homolog of MASP-1, plays an important role in complement activation; however, its direct interaction with PAR4 has not yet been elucidated. In this study, we performed structural investigations of thrombin, MASP-1, and MASP-2 to evaluate their binding affinities toward the PAR4 peptide.

We employed in silico docking, binding affinity calculations, molecular dynamics simulations, and mutagenesis studies to test our hypothesis.

For the first time, we demonstrate that, like thrombin and MASP-1, MASP-2 binds to PAR4 with appreciable affinity and could serve as a potential agonist of the PAR4 receptor and its associated inflammatory signaling pathways.

The high sequence similarity of MASP-2 with MASP-1 and thrombin is an important factor in attaining comparable binding with the PAR4 peptide.

Our findings may pave the way for future investigations into the signaling mechanisms and therapeutic potential of PAR4-mediated inflammatory diseases.