Amino acid residues of the FXIII-A₂intersubunit interface involved in intersubunit interactions. Amino acid residues of the FXIII-A monomer shown as yellow ribbon are depicted against the gray space–filled model of the opposite FXIII-A monomer. Ten amino acid residues are involved in salt bridge and H-bond formation and suggested to form 5 particularly strong interactions (highlighted in the orange box) between the two A-subunits.