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The gamma-carboxyglutamic acid and epidermal growth factor-like modules of factor IXa beta. Effects on the serine protease module and factor X activation

Astermark, Jan LU ; Hogg, Philip J and Stenflo, Johan LU (1994) In Journal of Biological Chemistry 269(5). p.3682-3689
Abstract
Blood coagulation factors IX and X are two serine proteases with a similar modular structure. The non-catalytic part of each protein consists of a gamma-carboxyglutamic acid (Gla)-containing module and two modules homologous to the epidermal growth factor (EGF) precursor. We have now found that the NH2-terminal EGF-like module of both factors IX and X inhibits factor Xa formation in a Gla-independent manner, both in the presence and absence of phospholipid and the cofactor, factor VIIIa. In contrast, the COOH-terminal EGF-like module has no such effect. Our data indicate that the NH2-terminal EGF-like module of factor IXa beta interacts either with the corresponding module or with the serine protease module in the substrate, factor X,... (More)
Blood coagulation factors IX and X are two serine proteases with a similar modular structure. The non-catalytic part of each protein consists of a gamma-carboxyglutamic acid (Gla)-containing module and two modules homologous to the epidermal growth factor (EGF) precursor. We have now found that the NH2-terminal EGF-like module of both factors IX and X inhibits factor Xa formation in a Gla-independent manner, both in the presence and absence of phospholipid and the cofactor, factor VIIIa. In contrast, the COOH-terminal EGF-like module has no such effect. Our data indicate that the NH2-terminal EGF-like module of factor IXa beta interacts either with the corresponding module or with the serine protease module in the substrate, factor X, without affecting the hydrolysis of low molecular weight substrates. Using antibodies as structural probes, we found that Ca2+ binding to the Gla module of factor IXa beta induces a conformational transition in the serine protease module. No evidence was found for a direct interaction between the Gla module and factor VIIIa. We therefore propose that the Gla module in factor IXa beta is indirectly involved in the cofactor interaction, in that Ca2+ binding to sites in this module induces a conformation in the serine protease module that is commensurate with factor VIIIa interaction. In addition, the immunochemical approach revealed a Gla-independent Ca2+ binding site in the serine protease module (apparent Kd of approximately 120 microM) that also might influence its conformation. Antibodies against the EGF-like modules of factor IX were used to probe Ca2+ binding to these modules in intact and in Gla-domainless factor IXa beta. The data indicate a Ca2+ binding site with an apparent Kd of approximately 50 microM in the NH2-terminal EGF-like module of both factor IX species. (Less)
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Contribution to journal
publication status
published
subject
in
Journal of Biological Chemistry
volume
269
issue
5
pages
3682 - 3689
publisher
ASBMB
external identifiers
  • pmid:8106413
ISSN
1083-351X
language
English
LU publication?
yes
id
805272db-a6ba-43f3-bf6d-38bbde4da53c (old id 1108477)
alternative location
http://www.jbc.org/cgi/reprint/269/5/3682
date added to LUP
2008-07-24 11:05:01
date last changed
2016-04-15 20:04:39
@article{805272db-a6ba-43f3-bf6d-38bbde4da53c,
  abstract     = {Blood coagulation factors IX and X are two serine proteases with a similar modular structure. The non-catalytic part of each protein consists of a gamma-carboxyglutamic acid (Gla)-containing module and two modules homologous to the epidermal growth factor (EGF) precursor. We have now found that the NH2-terminal EGF-like module of both factors IX and X inhibits factor Xa formation in a Gla-independent manner, both in the presence and absence of phospholipid and the cofactor, factor VIIIa. In contrast, the COOH-terminal EGF-like module has no such effect. Our data indicate that the NH2-terminal EGF-like module of factor IXa beta interacts either with the corresponding module or with the serine protease module in the substrate, factor X, without affecting the hydrolysis of low molecular weight substrates. Using antibodies as structural probes, we found that Ca2+ binding to the Gla module of factor IXa beta induces a conformational transition in the serine protease module. No evidence was found for a direct interaction between the Gla module and factor VIIIa. We therefore propose that the Gla module in factor IXa beta is indirectly involved in the cofactor interaction, in that Ca2+ binding to sites in this module induces a conformation in the serine protease module that is commensurate with factor VIIIa interaction. In addition, the immunochemical approach revealed a Gla-independent Ca2+ binding site in the serine protease module (apparent Kd of approximately 120 microM) that also might influence its conformation. Antibodies against the EGF-like modules of factor IX were used to probe Ca2+ binding to these modules in intact and in Gla-domainless factor IXa beta. The data indicate a Ca2+ binding site with an apparent Kd of approximately 50 microM in the NH2-terminal EGF-like module of both factor IX species.},
  author       = {Astermark, Jan and Hogg, Philip J and Stenflo, Johan},
  issn         = {1083-351X},
  language     = {eng},
  number       = {5},
  pages        = {3682--3689},
  publisher    = {ASBMB},
  series       = {Journal of Biological Chemistry},
  title        = {The gamma-carboxyglutamic acid and epidermal growth factor-like modules of factor IXa beta. Effects on the serine protease module and factor X activation},
  volume       = {269},
  year         = {1994},
}