Guanine nucleotide regulation of phospholipase C activity in permeabilized rabbit neutrophils. Inhibition by pertussis toxin and sensitization to submicromolar calcium concentrations

Rabbit neutrophils labelled with [3H]inositol and permeabilized with saponin produced [3H]inositol trisphosphate (InsP3) when incubated with stable analogues of GTP or millimolar concentrations of Ca2+. [3H]InsP3 production elicited by guanosine 5'-[gamma-thio]triphosphate was enhanced by the c...

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Bibliographic Details
Published in:Biochemical journal 1986-10, Vol.239 (1), p.97-102
Main Authors: Bradford, P G, Rubin, R P
Format: Article
Language:English
Subjects:
Adenosine Diphosphate - metabolism
Animals
Bordetella pertussis
calcium
Calcium - pharmacology
Cell Membrane Permeability
guanine nucleotides
Guanine Nucleotides - pharmacology
Guanosine 5'-O-(3-Thiotriphosphate)
Guanosine Triphosphate - analogs & derivatives
Guanosine Triphosphate - pharmacology
Inositol 1,4,5-Trisphosphate
Inositol Phosphates - metabolism
leukocytes (neutrophilic)
N-Formylmethionine Leucyl-Phenylalanine - pharmacology
Neutrophils - drug effects
Neutrophils - enzymology
Pertussis Toxin
phospholipase C
Rabbits
Thionucleotides - pharmacology
toxins
Type C Phospholipases - metabolism
Virulence Factors, Bordetella - pharmacology
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Summary:Rabbit neutrophils labelled with [3H]inositol and permeabilized with saponin produced [3H]inositol trisphosphate (InsP3) when incubated with stable analogues of GTP or millimolar concentrations of Ca2+. [3H]InsP3 production elicited by guanosine 5'-[gamma-thio]triphosphate was enhanced by the chemoattractant formylmethionyl-leucyl-phenylalanine and inhibited by pertussis-toxin pretreatment. A pertussis-toxin-sensitive stimulation of [3H]InsP3 concentration was also observed with guanosine 5'-[beta gamma-imido]triphosphate, but not with guanosine 5'-[beta-thio]diphosphate or GTP. Millimolar Ca2+ alone was sufficient to stimulate [3H]InsP3 production; however, in the presence of guanosine 5'-[gamma-thio]triphosphate, the Ca2+ dose-response curve was shifted to submicromolar concentrations. These findings directly confirm the role of a pertussis-toxin-sensitive guanine nucleotide regulatory protein (G protein) in chemoattractant-stimulated phospholipase C activity in rabbit neutrophils. Moreover, the ability of guanine nucleotides to sensitize phospholipase C to physiologically relevant Ca2+ concentrations suggests that the role of the activated G protein may be to enhance the apparent affinity of phospholipase C for Ca2+ and thus to activate the enzyme without an increase in the Ca2+ concentration.
ISSN:0264-6021
1470-8728
DOI:10.1042/bj2390097