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Regulation of platelet activating factor receptor coupled phosphoinositide-specific phospholipase C activity

Thesis/Dissertation ·
OSTI ID:6948246
The major objectives of this study were two-fold. The first was to establish whether binding of platelet activating factor (PAF) to its receptor was integral to the stimulation of polyphosphoinositide-specific phospholipase C (PLC) in rabbit platelets. The second was to determine regulatory features of this receptor-coupled mechanism. ({sup 3}H)PAF binding demonstrated two binding sites, a high affinity site with a inhibitory constant (Ki) of 2.65 nM and a low affinity site with a Ki of 0.80 {mu}M. PAF receptor coupled activation of phosphoinositide-specific PLC was studied in platelets which were made refractory, by short term pretreatments, to either PAF or thrombin. Saponin-permeabilized rabbit platelets continue to regulate the mechanism(s) coupling PAF receptors to PLC stimulation. However, TRP{gamma}S and GDP{beta}S, which affect guanine nucleotide regulatory protein functions, were unable to modulate the PLC activity to any appreciable extent as compared to PAF. The possible involvement of protein kinase C (PKC) activation in regulating PAF-stimulated PLC activity was studied in rabbit platelets pretreated with staurosporine followed by pretreatments with PAF or phorbol 12-myristate 13-acetate (PMA).
Research Organization:
Missouri Univ., Columbia, MO (USA)
OSTI ID:
6948246
Country of Publication:
United States
Language:
English

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550201* -- Biochemistry-- Tracer Techniques
560300 -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMALS
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BLOOD COAGULATION FACTORS
BLOOD PLATELETS
BODY FLUIDS
CARBOXYLESTERASES
CARCINOGENS
COAGULANTS
DRUGS
ENZYME ACTIVITY
ENZYMES
ESTERASES
ESTERS
HEMATOLOGIC AGENTS
HYDROGEN COMPOUNDS
HYDROLASES
ISOTOPE APPLICATIONS
KINETICS
LIPASES
MAMMALS
MATERIALS
MEMBRANE PROTEINS
ORGANIC COMPOUNDS
PHORBOL ESTERS
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
PROTEINS
RABBITS
REACTION KINETICS
RECEPTORS
TRACER TECHNIQUES
TRANSFERASES
TRITIUM COMPOUNDS
VERTEBRATES