Linked Life Data

2144523

Source:http://linkedlifedata.com/resource/pubmed/id/2144523

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
27
pubmed:dateCreated
1990-10-18
pubmed:abstractText
The interaction of protein S with membranes and subsequent combination with complement C4b-binding protein (C4BP) was studied. Protein S interacted with phospholipid vesicles in a calcium-dependent manner typical of other vitamin K-dependent proteins. Association of C4BP with protein S showed no apparent selectivity for membrane-bound or solution phase protein S. When bound to the membrane, the protein complexes projected out from the vesicle surface and induced vesicle radius changes of 11.4 nm for tightly packed protein S alone and 17.5 nm for the protein S-C4BP complex. Due to a low density of the protein S-C4BP on the membrane at saturation, the actual projection of this complex out from the membrane surface would be much greater than 17.5 nm. A low saturation density suggested that the protein complex had a large two-dimensional hydrodynamic radius in the plane of the membrane that prevented tight packing of protein. In the presence of calcium, the protein-protein interaction was rapid (ka greater than or equal to 1.10(6) M-1 s-1) and had very high affinity (KD less than or equal to 10(-10) M). The dissociation rate was slow with an estimated rate constant of less than or equal to 2.10(-4) s-1 at 25 degrees C. Protein-protein interaction was much slower in the absence of calcium with an estimated association rate constant of only 2.10(4) M-1 s-1. Consequently, the protein-protein interaction was greatly enhanced by calcium. The very high affinity interaction between protein S and C4BP suggested specificity and an important function for the protein S-C4BP complex in blood. In this regard it was important that C4BP which was bound to protein S on the phospholipid surface could interact with complement protein C4b. These results suggested that protein S may serve an important role in localizing C4BP to negatively charged phospholipid. This would provide regulation of complement activation at sites where the coagulation system is activated such as on the surface of activated platelets.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
265
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
16074-81
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:2144523-Animals, pubmed-meshheading:2144523-Calcium, pubmed-meshheading:2144523-Carrier Proteins, pubmed-meshheading:2144523-Cattle, pubmed-meshheading:2144523-Complement C4b, pubmed-meshheading:2144523-Complement Inactivator Proteins, pubmed-meshheading:2144523-Glycoproteins, pubmed-meshheading:2144523-Humans, pubmed-meshheading:2144523-Kinetics, pubmed-meshheading:2144523-Light, pubmed-meshheading:2144523-Liposomes, pubmed-meshheading:2144523-Membrane Proteins, pubmed-meshheading:2144523-Membranes, pubmed-meshheading:2144523-Models, Biological, pubmed-meshheading:2144523-Phosphatidylcholines, pubmed-meshheading:2144523-Phosphatidylserines, pubmed-meshheading:2144523-Protein Conformation, pubmed-meshheading:2144523-Protein S, pubmed-meshheading:2144523-Scattering, Radiation
pubmed:year
1990
pubmed:articleTitle
Assembly of protein S and C4b-binding protein on membranes.
pubmed:affiliation
Department of Biochemistry, University of Minnesota, St. Paul 55108.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't