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FXIIa, PKa activate coagulation factors

Summary

Organism

Homo sapiens (human)

Reactome

R-HSA-9935598

PubChem

R-HSA-9935598

Description

Activated factor FXII (FXIIa) promotes fibrin clot formation by converting FXI to FXIa (Cheng Q et al., 2010), while plasma kallikrein directly binds and activates FIX (Kearney KJ et al., 2021), thereby facilitating crosstalk between coagulation and inflammation. Despite this, both FXII and plasma kallikrein are non-essential for normal hemostatic pathway, as individuals deficient in FXII or prekallikrein do not exhibit bleeding disorders (Kokoye Y et al., 2016). At the same time, studies using animal disease models suggest that these factors may contribute to thrombotic events under pathological conditions (Revenko AS et al., 2011; Matafonov A et al., 2014; reviewed by Schmaier A, 2016). Deficiencies of FXII, prekallikrein (PK), high molecular weight kininogen (HK), and the bradykinin B2 receptor are associated with prolonged thrombin generation times in murine models of arterial and venous thrombosis (Pauer HU et al., 2004, Stavrou EV et al., 2015, Merkulov S et al., 2008, Shariat-Madar Z et al., 2006; Fang C et al., 2013). Alternatively, FXI null mice exhibit a bleeding phenotype, whereas prolylcarboxypeptidase- and C1 inhibitor-deficient mice display a prothrombotic phenotype (Gailani D et al., Adams GA et al., 2011; Grover S et al., 2023). Large population studies indicate that FXII deficiency protects against venous thrombosis, whereas C1 inhibitor deficiency is associated with increased thrombotic risk (Haj AK et al., 2025; Rodriguez Espada A et al., 2026).

Click on a node on the pathway to see its details. Glycoproteins are marked with a glycoprotein icon in their name.

SPV: a JavaScript Signaling Pathway Visualizer, Bioinformatics, 2018

Displaying **all 9** entries
UniProt ID	Protein Name	Gene Symbol	Pathway Viewer
P00740	Coagulation factor IX	F9	view
P00748	Coagulation factor XII	F12	view
P01042	Kininogen-1	BDK KNG KNG1	view
P03951	Coagulation factor XI	F11	view
P03952	Plasma kallikrein	KLK3 KLKB1	view
P07359	Platelet glycoprotein Ib alpha chain	GP1BA	view
P13224	Platelet glycoprotein Ib beta chain	GP1BB	view
P14770	Platelet glycoprotein IX	GP9	view
P40197	Platelet glycoprotein V	GP5	view

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