These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Direct demonstration that the vitamin K-dependent bone Gla protein is incompletely gamma-carboxylated in humans.
    Author: Cairns JR, Price PA.
    Journal: J Bone Miner Res; 1994 Dec; 9(12):1989-97. PubMed ID: 7872066.
    Abstract:
    Incomplete vitamin K-dependent gamma-carboxylation has been found in bone Gla protein (BGP) isolated from each of 20 different human bone samples. Using N-terminal protein sequencing of the methyl-esterified protein (Anal Biochem 1991;199:93-97), a method that directly measures the percentage of gamma-carboxylation at each target glutamate residue, the extent of incomplete BGP gamma-carboxylation was found to depend strongly on sequence position, with (chi +/- SD) 67 +/- 14% gamma-carboxylation at residue 17.88 +/- 9% gamma-carboxylation at residue 21, and 93 +/- 4% gamma-carboxylation at residue 24. There is a strong correlation between the incomplete gamma-carboxylation at glutamate residues 17 and 21 for BGP purified from the 20 bone samples (p < 0.001), which suggests that individual differences in the efficiency of BGP gamma-carboxylation during synthesis probably cause the observed differences in percentage BGP gamma-carboxylation between bone samples. These results have been interpreted using a kinetic treatment of gamma-carboxylation. This treatment predicts the existence of differences in the extent of gamma-carboxylation between glutamate residues in BGP, as well as the correlation between percentage carboxylation at Glu17 and Glu21. Although the molecular basis of incomplete BGP gamma-carboxylation is at present unknown, if incomplete BGP gamma-carboxylation were caused only by differences in the availability of vitamin K in bone cells, this kinetic treatment predicts that the range in BGP gamma-carboxylation observed in the 20 human bone samples studied here could be explained by a relatively modest fivefold range in the vitamin K levels of these individuals.
    [Abstract] [Full Text] [Related] [New Search]