PDBsum entry 4ch2

Hydrolase/peptide

PDB id: 4ch2

Contents

Protein chains

32 a.a.

258 a.a.

29 a.a.

Ligands

ASP-LEU-PTR-ASP-PTR-PTR-PRO

THR-ASP-LEU-PTR-ASP-PTR-PTR-PRO

GOL ×4

0G6 ×2

Metals

_NA ×2

Waters ×473

PDB id:

4ch2

Name:

Hydrolase/peptide

Title:

Low-salt crystal structure of a thrombin-gpibalpha peptide complex

Structure:

Thrombin, light chain. Chain: a, c. Synonym: coagulation factor ii. Engineered: yes. Thrombin, heavy chain. Chain: b, d. Engineered: yes. Platelet glycoprotein ib alpha chain, residues 287-300. Chain: p, q.

Source:

Homo sapiens. Human. Organism_taxid: 9606. Expressed in: escherichia coli. Expression_system_taxid: 469008. Expression_system_variant: star, plyss. Synthetic: yes. Organism_taxid: 9606

Resolution:

1.60Å R-factor: 0.156 R-free: 0.187

Authors:

B.C.Lechtenberg,S.M.V.Freund,J.A.Huntington

Key ref:

B.C.Lechtenberg et al. (2014). GpIbα interacts exclusively with exosite II of thrombin. J Mol Biol, 426, 881-893. PubMed id: 24316004 DOI: 10.1016/j.jmb.2013.11.027

Date:

28-Nov-13 Release date: 11-Dec-13

Protein chain

P00734  (THRB_HUMAN) -  Prothrombin from Homo sapiens

Seq: 622 a.a.

Struc: 32 a.a.

Protein chains

P00734  (THRB_HUMAN) -  Prothrombin from Homo sapiens

Seq: 622 a.a.

Struc: 258 a.a.

Protein chain

P00734  (THRB_HUMAN) -  Prothrombin from Homo sapiens

Seq: 622 a.a.

Struc: 29 a.a.

Enzyme reactions

• Enzyme class: Chains A, B, C, D: E.C.3.4.21.5 - thrombin.
• Reaction: Preferential cleavage: Arg-|-Gly; activates fibrinogen to fibrin and releases fibrinopeptide A and B.

DOI no: 10.1016/j.jmb.2013.11.027

J Mol Biol 426:881-893 (2014)

PubMed id: 24316004

GpIbα interacts exclusively with exosite II of thrombin.

B.C.Lechtenberg, S.M.Freund, J.A.Huntington.

ABSTRACT

Activation of platelets by the serine protease thrombin is a critical event in haemostasis. This process involves the binding of thrombin to glycoprotein Ibα (GpIbα) and cleavage of protease-activated receptors (PARs). The N-terminal extracellular domain of GpIbα contains an acidic peptide stretch that has been identified as the main thrombin binding site, and both anion binding exosites of thrombin have been implicated in GpIbα binding, but it remains unclear how they are involved. This issue is of critical importance for the mechanism of platelet activation by thrombin. If both exosites bind to GpIbα, thrombin could potentially act as a platelet adhesion molecule or receptor dimerisation trigger. Alternatively, if only a single site is involved, GpIbα may serve as a cofactor for PAR-1 activation by thrombin. To determine the involvement of thrombin's two exosites in GpIbα binding, we employed the complementary methods of mutational analysis, binding studies, X-ray crystallography and NMR spectroscopy. Our results indicate that the peptide corresponding to the C-terminal portion of GpIbα and the entire extracellular domain bind exclusively to thrombin's exosite II. The interaction of thrombin with GpIbα thus serves to recruit thrombin activity to the platelet surface while leaving exosite I free for PAR-1 recognition.