A receptor and G-protein-regulated polyphosphoinositide-specific phospholipase C from turkey erythrocytes. II. P2Y-purinergic receptor and G-protein-mediated regulation of the purified enzyme reconstituted with turkey erythrocyte ghosts

J Biol Chem. 1990 Aug 15;265(23):13508-14.

Abstract

The preceding paper describes purification and properties of a 150-kDa polyphosphoinositide-specific phospholipase C from a cytosolic fraction of turkey erythrocytes (Morris, A. J., Waldo, G. L., Downes, C. P., and Harden, T. K. (1990) J. Biol. Chem. 265, 13501-13507). Turkey erythrocytes express a P2Y-purinergic receptor that employs an unidentified G-protein to activate phospholipase C (Boyer, J. L., Downes, C. P., and Harden, T. K. (1989) J. Biol. Chem. 264, 884-890; Cooper, C. L., Morris, A. J., and Harden, T. K. (1989) J. Biol. Chem. 264, 6202-6206). This paper describes receptor and G-protein regulation of the purified turkey erythrocyte phospholipase C after reconstitution of the enzyme using [3H]inositol pre-labeled turkey erythrocyte ghosts as acceptor membranes. These membranes contain polyphosphoinositides labeled to high specific radioactivity and display reduced responsiveness of their endogenous phospholipase C to P2Y-purinergic receptor agonists and guanine nucleotides. Reconstitution of purified enzyme had no effect on basal inositol phosphate production, but markedly increased P2Y-purinergic receptor agonist and guanine nucleotide-dependent accumulation of inositol phosphates. Reconstitution of 5 ng of purified phospholipase C with 10 micrograms of acceptor membrane protein produced half-maximal effects, and maximal activity was observed with reconstitution of 100 ng of purified enzyme. Agonist and guanine nucleotide-regulated phospholipase C activity measured using a reconstitution assay co-purified with phospholipase C activity detected using exogenously provided phosphatidylinositol 4,5-bisphosphate during purification of the 150-kDa protein. Only the maximal rate of inositol phosphate formation attained upon activation was increased in the presence of the purified phospholipase C. K0.5 values for adenosine 5'-O-(2-thiodiphosphate), guanosine 5'-3-O-(thio)triphosphate, and A1F4- activation of the purified enzyme were the same as for the endogenous phospholipase C activity of the acceptor membranes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Diphosphate / analogs & derivatives
  • Adenosine Diphosphate / pharmacology
  • Animals
  • Calcium / pharmacology
  • Enzyme Activation
  • Erythrocyte Membrane / metabolism*
  • Erythrocytes / enzymology*
  • GTP-Binding Proteins / blood*
  • GTP-Binding Proteins / physiology
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Guanosine Triphosphate / analogs & derivatives
  • Guanosine Triphosphate / pharmacology
  • Inositol / blood
  • Inositol Phosphates / blood
  • Kinetics
  • Phosphoinositide Phospholipase C
  • Phosphoric Diester Hydrolases / blood*
  • Phosphoric Diester Hydrolases / isolation & purification
  • Receptors, Purinergic / physiology*
  • Thionucleotides / pharmacology
  • Turkeys

Substances

  • Inositol Phosphates
  • Receptors, Purinergic
  • Thionucleotides
  • adenosine 5'-O-(2-thiodiphosphate)
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Inositol
  • Adenosine Diphosphate
  • Guanosine Triphosphate
  • Phosphoric Diester Hydrolases
  • Phosphoinositide Phospholipase C
  • GTP-Binding Proteins
  • Calcium