Fibrin

Function

Fibrin (or Factor Ia, FIa) is a fibrous protein which when polymerized is involved in blood clotting. The polymerization epitopes of FIa are called A-knob and B-knob. Fibrinogen (Factor I, FI) is converted by thrombin to fibrin. Limited proteolysis of FI results in a fragment named D which when cross-linked by factor XIII is called double-D FIa (DDFIa)^[1].

Disease

Overexpression of FIa can cause thrombosis.

Structural highlights

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(PDB entry 1n73).

Fibrin α1 subunit (red, yellow), β subunit (cyan, blue), γ subunit (orange, magenta) from Petromyzon marinus (PDB entry 1n73)

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3D Structures of Fibrin3D Structures of Fibrin

Updated on 02-March-2023

3h32 – hFIa peptide+ hFI α, β, γ chains – human
2q9i, 2z4e - hFIa B-knob+ hFI α, β, γ chains
2hlo, 1n86 - hFIa α, β, γ chains + peptide
1n8e - hFIa α, β, γ chains
2a45 - hFIa α, β, γ chains + thrombin
1fzc – hDDFIa+peptide
1n73 - FIa α, β, γ chains + peptide – Sea lamprey

ReferencesReferences

↑ Yang Z, Pandi L, Doolittle RF. The crystal structure of fragment double-D from cross-linked lamprey fibrin reveals isopeptide linkages across an unexpected D-D interface. Biochemistry. 2002 Dec 31;41(52):15610-7. PMID:12501189

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Alexander Berchansky, Michal Harel

[1] Yang Z, Pandi L, Doolittle RF. The crystal structure of fragment double-D from cross-linked lamprey fibrin reveals isopeptide linkages across an unexpected D-D interface. Biochemistry. 2002 Dec 31;41(52):15610-7. PMID:12501189

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