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Binding of fibrinogen to platelet integrin αIIbβ3 in solution as monitored by tracer sedimentation equilibrium
Author(s) -
Rivas Germán,
Tangemann Kirsten,
Minton Allen P.,
Engel Jürgen
Publication year - 1996
Publication title -
journal of molecular recognition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.401
H-Index - 79
eISSN - 1099-1352
pISSN - 0952-3499
DOI - 10.1002/(sici)1099-1352(199601)9:1<31::aid-jmr237>3.0.co;2-o
Subject(s) - fibrinogen , tracer , sedimentation equilibrium , sedimentation , platelet , integrin , chemistry , biochemistry , medicine , biology , physics , ultracentrifuge , receptor , paleontology , sediment , nuclear physics
Fibrinogen showed essentially no binding ( K D >1 m M ) to platelet αIIbβ3 integrin in solution in the presence of Triton or octylglucoside above critical micellar concentrations. Under these conditions the integrin was an αβ monomer. After removal of the detergent from the Triton containing buffer (25 m M Tris/HCl;, 150 m M NaCl, 1 m M CaCl 2 , 1 m M MgCl 2 , pH 7.4) the integrin formed aggregates with hexamers as the most prominent species, as demonstrated by analytical ultracentrifugation and electron microscopy. Tracer sedimentation equilibrium experiments indicate that fibrinogen binds to the integrin aggregates, but with a surprisingly large K D (at least 3 μ M ). This value is 10‐ to 100‐fold higher than values determined by solid phase assays or with integrins reconstituted onto lipid bilayers.