RGD induces conformational transition in purified platelet integrin GPIIb/IIIa-SDS system yielding multiple binding states for fibrinogen gamma-chain C-terminal peptide.
Fibrinogen gamma-chain C-terminal peptide HHLG-GAKQAGDV (gamma 12) and alpha-chain peptide GRGDSP are known to inhibit fibrinogen-mediated platelet cell aggregation via competitive interactions with platelet integrin receptor GPIIb/IIIa. NMR studies of gamma 12 in the presence of purified GPIIb/IIIa in SDS/water solution have demonstrated the presence of two gamma 12 binding states, one of which is eliminated by GRGDSP (RGD) up to a RGD: gamma 12 ratio of 2:1. RGD: gamma 12 ratios greater than 2:1 produce multiple sets of gamma 12 NMR signals in TOCSY spectra. At a ratio of 4:1, two to four such resonance sets can be resolved for A405, Q407, A408, G409, D410 and V411 spin systems. The number of multiple resonances remains unchanged at ratios of 6:1 and 8:1. Addition of gamma 12 to reverse the ratio to 8:8 (1:1) has no apparent effect on the RGD-induced distribution. Results suggest that RGD irreversibly induces a conformational transition(s) in GPIIb/IIIa to produce multiple gamma 12 binding sites on the receptor.
Department of Biochemistry, University of Minnesota, Minneapolis 55455, USA.
K H
KH
Mayo
F
F
Fan
M P
MP
Beavers
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A
Eckardt
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Keane
W J
WJ
Hoekstra
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Andrade-Gordon
D000595:Amino Acid Sequence; D001665:Binding Sites; D001792:Blood Platelets / Q000737:chemistry*; D005340:Fibrinogen / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000494:pharmacology*; D010446:Peptide Fragments / Q000378:metabolism*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation / Q000187:drug effects
D009842:Oligopeptides; D010446:Peptide Fragments; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; C047981:arginyl-glycyl-aspartic acid; D005340:Fibrinogen