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Urinary protein C inhibitor binding region in the A alpha-chain of human fibrinogen

S Hayashi1, A Wakizaka

  • 1Thrombosis Chemical Institute, Tokyo, Japan.

Blood Coagulation & Fibrinolysis : an International Journal in Haemostasis and Thrombosis
|July 1, 1995
PubMed

Insights

Researchers identified the binding site of urinary protein C inhibitor (PCI) on human fibrinogen's A alpha-chain. The study pinpointed the region between amino acids I250 and E357 (or E370) as the key interaction zone for PCI binding.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Protein Interactions

Background:

  • Urinary protein C inhibitor (PCI) plays a crucial role in regulating coagulation.
  • Understanding PCI's interaction with fibrinogen is essential for elucidating its physiological functions.
  • The specific binding region of PCI within human fibrinogen has not been precisely defined.

Purpose of the Study:

  • To identify and characterize the precise binding region of urinary protein C inhibitor (PCI) on the A alpha-chain of human fibrinogen.

Main Methods:

  • Human fibrinogen A alpha-chain was digested using staphylococcal V8 protease.
  • Peptides were separated by SDS-PAGE and transferred to membranes for ligand blotting with urinary PCI.
  • N-terminal amino acid sequencing was performed on PCI-binding peptides using Edman degradation and mass spectrometry.

Main Results:

  • Several peptides bound to urinary PCI, with the 14 kDa band being the most prominent.
  • N-terminal sequencing of the binding peptides consistently revealed the sequence ITRGGST.
  • This sequence corresponds to residues I250 to T256 in the A alpha-chain.
  • Further analysis refined the binding region to be between I250 and E357 (or E370) of the A alpha-chain.

Conclusions:

  • The study successfully mapped the urinary PCI binding region to a specific segment of the human fibrinogen A alpha-chain.
  • The identified region, spanning from I250 to E357 (or E370), is critical for the interaction between urinary PCI and fibrinogen.

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