Biomaterial Database

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. 1990

A J Morris, and G L Waldo, and C P Downes, and T K Harden

Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill 27599.

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.

UI	MeSH Term	Description	Entries
D007294	Inositol	An isomer of glucose that has traditionally been considered to be a B vitamin although it has an uncertain status as a vitamin and a deficiency syndrome has not been identified in man. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1379) Inositol phospholipids are important in signal transduction.	Myoinositol,Chiro-Inositol,Mesoinositol,Chiro Inositol
D007295	Inositol Phosphates	Phosphoric acid esters of inositol. They include mono- and polyphosphoric acid esters, with the exception of inositol hexaphosphate which is PHYTIC ACID.	Inositol Phosphate,Phosphate, Inositol,Phosphates, Inositol
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D010727	Phosphoric Diester Hydrolases	A class of enzymes that catalyze the hydrolysis of one of the two ester bonds in a phosphodiester compound. EC 3.1.4.	Phosphodiesterase,Phosphodiesterases,Hydrolases, Phosphoric Diester
D011983	Receptors, Purinergic	Cell surface proteins that bind PURINES with high affinity and trigger intracellular changes which influence the behavior of cells. The best characterized classes of purinergic receptors in mammals are the P1 receptors, which prefer ADENOSINE, and the P2 receptors, which prefer ATP or ADP.	Methyladenine Receptors,Purine Receptors,Purinergic Receptor,Purinergic Receptors,Purinoceptors,Purine Receptor,Purinoceptor,Receptors, Methyladenine,Receptors, Purine,Receptor, Purine,Receptor, Purinergic
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D004789	Enzyme Activation	Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.	Activation, Enzyme,Activations, Enzyme,Enzyme Activations
D004910	Erythrocyte Membrane	The semi-permeable outer structure of a red blood cell. It is known as a red cell 'ghost' after HEMOLYSIS.	Erythrocyte Ghost,Red Cell Cytoskeleton,Red Cell Ghost,Erythrocyte Cytoskeleton,Cytoskeleton, Erythrocyte,Cytoskeleton, Red Cell,Erythrocyte Cytoskeletons,Erythrocyte Ghosts,Erythrocyte Membranes,Ghost, Erythrocyte,Ghost, Red Cell,Membrane, Erythrocyte,Red Cell Cytoskeletons,Red Cell Ghosts
D004912	Erythrocytes	Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.	Blood Cells, Red,Blood Corpuscles, Red,Red Blood Cells,Red Blood Corpuscles,Blood Cell, Red,Blood Corpuscle, Red,Erythrocyte,Red Blood Cell,Red Blood Corpuscle
D006160	Guanosine Triphosphate	Guanosine 5'-(tetrahydrogen triphosphate). A guanine nucleotide containing three phosphate groups esterified to the sugar moiety.	GTP,Triphosphate, Guanosine