Membrane-associated 41-kDa GTP-binding protein in collagen-induced platelet activation

Journal Article · Wed Aug 01 04:00:00 EDT 1990 · FASEB Journal (Federation of American Societies for Experimental Biology); (USA)

OSTI ID:6623020

Walker, G; Bourguignon, L Y ^[1]

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1. Univ. of Miami Medical School, FL (USA)

Initially we established that the binding of collagen to human blood platelets stimulates both the rapid loss of PIP2 and the generation of inositol-4,5-bisphosphate (IP2) and inositol-1,4,5-triphosphate (IP3). These results indicate that the binding of collagen stimulates inositol phospholipid-specific phospholipase C during platelet activation. The fact that GTP or GTP-gamma-S augments, and pertussis toxin inhibits, collagen-induced IP3 formation suggests that a GTP-binding protein or (or proteins) may be directly involved in the regulation of phospholipase C-mediated phosphoinositide turnover in human platelets. We have used several complementary techniques to isolate and characterize a platelet 41-kDa polypeptide (or polypeptides) that has a number of structural and functional similarities to the regulatory alpha i subunit of the GTP-binding proteins isolated from bovine brain. This 41-kDa polypeptide (or polypeptides) is found to be closely associated with at least four membrane glycoproteins (e.g., gp180, gp110, gp95, and gp75) in a 330-kDa complex that can be dissociated by treatment with high salt plus urea. Most important, we have demonstrated that antilymphoma 41-kDa (alpha i subunit of GTP-binding proteins) antibody cross-reacts with the platelet 41-kDa protein (or proteins) and the alpha i subunit of bovine brain Gi alpha proteins, and blocks GTP/collagen-induced IP3 formation. These data provide strong evidence that the 41-kDa platelet GTP-binding protein (or proteins) is directly involved in collagen-induced signal transduction during platelet activation.

• OSTI ID: 6623020
• Journal Information: FASEB Journal (Federation of American Societies for Experimental Biology); (USA), Journal Name: FASEB Journal (Federation of American Societies for Experimental Biology); (USA) Vol. 4:11; ISSN FAJOE; ISSN 0892-6638
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADP
ANTIGENS
AUTORADIOGRAPHY
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL FUNCTIONS
BIOLOGICAL MATERIALS
BIOSYNTHESIS
BLOOD
BLOOD CELLS
BLOOD PLATELETS
BODY FLUIDS
CARBOXYLESTERASES
COLLAGEN
ENZYME ACTIVITY
ENZYMES
ESTERASES
ESTERS
FUNCTIONS
HYDROLASES
INHIBITION
ISOTOPES
KINETICS
LIPASES
LIPIDS
MATERIALS
MEMBRANE PROTEINS
MOLECULAR WEIGHT
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHOLIPIDS
PHOSPHORUS ISOTOPES
PROTEINS
REACTION KINETICS
SCLEROPROTEINS
SYNTHESIS
TOXIC MATERIALS
TOXINS