Title: Osteocalcin binds tightly to the gamma-glutamylcarboxylase at a site distinct from that of the other known vitamin K-dependent proteins
Authors: Houben, RJ ×
Jin, D
Stafford, DW
Proost, Paul
Ebberink, RH
Vermeer, C
Soute, BA #
Issue Date: 15-Jul-1999
Publisher: Published by Portland Press on behalf of the Biochemical Society
Series Title: Biochemical Journal vol:341 issue:Pt 2 pages:265-269
Abstract: Vitamin K-dependent proteins contain a propeptide that is required for recognition by the enzyme gamma-glutamylcarboxylase. Substrates used in vitro for carboxylation studies lacking a prosequence are characterized by Km values in the millimolar range, whereas the Km for peptides containing a prosequence is three or four orders of magnitude smaller. Here we report that descarboxy-osteocalcin is an exception in this respect. With descarboxy-osteocalcin in purified propeptide-free recombinant carboxylase, the Km was 1.8 microM. Furthermore, osteocalcin was an inhibitor of descarboxy-osteocalcin carboxylation with a Ki of 76 microM. In contrast with the other vitamin K-dependent proteins, free propeptides do not inhibit descarboxy-osteocalcin carboxylation. Moreover, propeptide-containing substrates were inhibited neither by osteocalcin nor by its propeptide. From our studies we conclude that descarboxy-osteocalcin must have an internal recognition sequence that binds to gamma-glutamylcarboxylase at a site different from the propeptide-recognition site.
ISSN: 0264-6021
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory of Molecular Immunology (Rega Institute)
× corresponding author
# (joint) last author

Files in This Item:

There are no files associated with this item.

Request a copy


All items in Lirias are protected by copyright, with all rights reserved.

© Web of science