Linked Life Data

10681521

Source:http://linkedlifedata.com/resource/pubmed/id/10681521

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
2000-3-30
pubmed:abstractText
The endothelial cell protein C receptor (EPCR) functions as an important regulator of the protein C anticoagulant pathway by binding protein C and enhancing activation by the thrombin-thrombomodulin complex. EPCR binds to both protein C and activated protein C (APC) with high affinity. A soluble form of EPCR (sEPCR) circulates in plasma and inhibits APC anticoagulant activity. In this study, we investigate the mechanisms by which sEPCR modulates APC function. Soluble EPCR inhibited the inactivation of factor Va by APC only in the presence of phospholipid vesicles. By using flow cytometric analysis in the presence of 3 mM CaCl(2) and 0. 6 mM MgCl(2), sEPCR inhibited the binding of protein C and APC to phospholipid vesicles (K(i) = 40 +/- 7 and 33 +/- 4 nM, respectively). Without MgCl(2), the K(i) values increased approximately 4-fold. Double label flow cytometric analysis using fluorescein-APC and Texas Red-sEPCR indicated that the APC.sEPCR complex does not interact with phospholipid vesicles. By using surface plasmon resonance, we found that sEPCR also inhibited binding of protein C to phospholipid in a dose-dependent fashion (K(i) = 32 nM). To explore the possibility that sEPCR evokes structural changes in APC, fluorescence spectroscopy studies were performed to monitor sEPCR/Fl-APC interactions. sEPCR binds saturably to Fl-APC (K(d) = 27 +/- 13 nM) with a maximum decrease in Fl-APC fluorescence of 10.8 +/- 0.6%. sEPCR also stimulated the amidolytic activity of APC toward synthetic substrates. We conclude that sEPCR binding to APC blocks phospholipid interaction and alters the active site of APC.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
275
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5447-52
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:10681521-Binding Sites, pubmed-meshheading:10681521-Blood Coagulation Factors, pubmed-meshheading:10681521-Calcium Chloride, pubmed-meshheading:10681521-Dose-Response Relationship, Drug, pubmed-meshheading:10681521-Enzyme Activation, pubmed-meshheading:10681521-Factor Va, pubmed-meshheading:10681521-Flow Cytometry, pubmed-meshheading:10681521-Humans, pubmed-meshheading:10681521-Kinetics, pubmed-meshheading:10681521-Liposomes, pubmed-meshheading:10681521-Magnesium Chloride, pubmed-meshheading:10681521-Protein Binding, pubmed-meshheading:10681521-Protein C, pubmed-meshheading:10681521-Protein Conformation, pubmed-meshheading:10681521-Protein S, pubmed-meshheading:10681521-Receptors, Cell Surface, pubmed-meshheading:10681521-Surface Plasmon Resonance, pubmed-meshheading:10681521-Time Factors
pubmed:year
2000
pubmed:articleTitle
Mechanisms by which soluble endothelial cell protein C receptor modulates protein C and activated protein C function.
pubmed:affiliation
Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't