What is the role of vitamin K in the pathophysiology of protein S deficiency?

Updated: Jan 03, 2021
  • Author: Mohammad Muhsin Chisti, MD, FACP; Chief Editor: Perumal Thiagarajan, MD  more...
  • Print
Answer

Protein S is a single-chain glycoprotein, and it is dependent on vitamin K action for posttranslational modification of the protein to a normal functional state. Vitamin K–dependent proteins are synthesized with a unique recognition propeptide piece. The propeptide sequence serves as a recognition site for the vitamin K–dependent gamma-carboxylase enzyme that modifies the nearby glutamic acid residues to gamma-carboxyglutamic acid (Gla) residues. Gla residues are responsible for calcium-dependent binding to membrane surfaces. Structural studies indicate that protein S contains 10-12 Gla residues, a loop region sensitive to thrombin (ie, thrombin-sensitive region [TSR]), 4 epidermal growth factor (EGF)–like modules, and a carboxy-terminal portion that is homologous to a sex hormone-binding globulin (SHBG)–like region.


Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!