Regulation of phosphoinositide hydrolysis and fibrinogen receptor expression by GTP regulatory protein(s) in isolated platelet membranes
Thrombin through a GTP-dependent mechanism, stimulated fibrinogen binding and indogenous (/sup 3/H) inositol- and (/sup 32/P)-labeled phosphoinositide hydrolysis in membranes prepared from platelets. Incubation of isolated membranes with GTP enhanced both fibrinogen binding and phosphoinositide metabolism in a dose dependent fashion with half-maximal activation at approximately 50..mu..m and 25..mu..m respectively. Addition of thrombin (l..mu../ml) or ADP (10..mu..M) and GTP enhanced fibrinogen lending 10-fold compared to GTP alone. Inositol triphosphate formation was increased by 300 to 500% within 60 seconds after the addition of thrombin (l..mu../ml). Addition of thrombin plus GTP, however, did not lead to the formation of inositol on glycerol phosphoinositol. These data suggest that in a cell free system these processes are mediated by guanine nucleotide binding regulatory protein(s). Although a general role for GTP-binding proteins in receptor-regulated processes is currently a popular idea, this data is the most direct evidence to date for a role in platelets other than the well established mediation of adenylate cyclase activity.
- Research Organization:
- American Red Cross, St. Louis, MO
- OSTI ID:
- 6898981
- Report Number(s):
- CONF-8606151-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Vol. 45:6; ISSN FEPRA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ADP
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BLOOD COAGULATION FACTORS
BLOOD PLATELETS
BODY FLUIDS
CARBOHYDRATES
CELL CONSTITUENTS
CELL MEMBRANES
CHEMISTRY
COAGULANTS
CYCLASES
DAYS LIVING RADIOISOTOPES
DRUGS
ENZYMES
ESTERS
FIBRINOGEN
GLOBULINS
GUANYLIC ACID
HEMATOLOGIC AGENTS
HEMOSTATICS
HYDROLASES
INOSITOL
INOSITOLS
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LABELLED COMPOUNDS
LIGHT NUCLEI
LIPIDS
LYASES
MATERIALS
MEMBRANE PROTEINS
MEMBRANES
METABOLISM
MOLECULAR BIOLOGY
MONOSACCHARIDES
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PEPTIDE HYDROLASES
PHOSPHOLIPIDS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RECEPTORS
SACCHARIDES
SERINE PROTEINASES
THROMBIN
TRACER TECHNIQUES
TRITIUM COMPOUNDS