Anchoring of bovine prothrombin to<unk> e membrane<unk> ough its Gla domain.<unk> e molecular weight of prothrombin is approximately 72,000 Da.<unk> e catalytic domain is released from prothrombin fragment 1.2 to create<unk> e active enzyme<unk> , which has a molecular weight of 36,000 Da. Structurally, it is a member of<unk> e large PA clan of proteases. Prothrombin is composed of four domains; an N-terminal Gla domain, two kringle domains and a C-terminal trypsin-like serine protease domain. Factor Xa with factor V as a cofactor leads to cleavage of<unk> e Gla and two Kringle domains (forming together a fragment called fragment 1.2) and leave<unk> , consisting solely of<unk> e serine protease domain. As is<unk> e case for all serine proteases, prothrombin is converted to active<unk>  by proteolysis of an internal peptide bond, exposing a new N-terminal Ile-NH3.<unk> e historic model of activation of serine proteases involves insertion of<unk> is newly formed N-terminus of<unk> e heavy chain into<unk> e β-barrel promoting<unk> e correct conformation of<unk> e catalytic residues. Contrary to crystal structures of active<unk> , hydrogen-deuterium exchange mass spectrometry studies indicate<unk> at<unk> is N-terminal Ile-NH3 does not become inserted into<unk> e β-barrel in<unk> e apo form of<unk> . However, binding of<unk> e active fragment of<unk> ombomodulin appears to allosterically promote<unk> e active conformation of<unk>  by inserting<unk> is N-terminal region.
Thrombin
Prothrombinase
Platelet-activating factor
Kallikrein
Plasminogen 
Fibrinolysin
Von Willebrand factor
Serpin