Localization of thrombin cleavage sites in the amino-terminal region of bovine protein S

• Protein S is a vitamin K-dependent plasma protein. It functions as a cofactor to activated protein C in the inactivation of factors Va and VIIIa by limited proteolysis. Protein S is very sensitive to proteolysis by thrombin which reduces its calcium ion binding and leads to a loss of its cofactor activity. We have now determined the sequence of the 100 amino-terminal amino acid residues and localized the thrombin cleavage sites. Protein S contains 11 gamma-carboxyglutamic acid residues in the amino-terminal region (residues 1-36). This part of protein S is highly homologous to the corresponding parts in the other vitamin K-dependent clotting factors, whereas the region between residues 45 and 75 is not at all homologous to the other clotting factors. Thrombin cleaves two peptide bonds in this part of protein S, first at arginine 70 and then at arginine 52. The peptide containing residues 53-70 is released from protein S after thrombin cleavage. The amino-terminal fragment, residues 1-52, is linked to the large carboxyl-terminal fragment by a disulfide bond, which involves cysteine 47. After residue 78, protein S is again homologous to factors IX and X and to proteins C and Z, but not to prothrombin. Position 95 is occupied by a beta-hydroxyaspartic acid residue.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Läkemedelskemi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Medicinal Chemistry (hsv//eng)

Nyckelord

Peptide Fragments/isolation & purification/*metabolism

Glycoproteins/*metabolism

Endopeptidases/metabolism

Disulfides/metabolism

Cyanogen Bromide

Chymotrypsin/metabolism

Cattle

Calcium/metabolism

Amino Acid Sequence

Animals

Protein S

Research Support

Non-U.S. Gov't

*Serine Endopeptidases

Thrombin/*metabolism

Publikations- och innehållstyp

art (ämneskategori)

ref (ämneskategori)