The Effect of F-actin on the Binding and Hydrolysis of Guanine Nucleotide byDictyosteliumElongation Factor 1A

The guanine nucleotides guanosine 5′[beta, gamma-imido]triphosphate (Gpp[NH]p), guanosine 5′-[γ-thio]-triphosphate (GTP gamma S), GMP, GDP and GTP stimulated the hydrolysis of inositol phospholipids by a phosphodiesterase in rat cerebral cortical membranes. Addition of 100 microM-Gpp[NH]p to prelabelled membranes caused a rapid accumulation of [3H)inositol phosphates (less than 30 s) for up to 2 min. GTP gamma S and Gpp [NH]p caused a concentration-dependent stimulation of phosphoinositide phosphodiesterase with a maximal stimulation of 2.5-3-fold over control at concentrations of 100 microM. GMP was as effective as the nonhydrolysable analogues, but much less potent (EC50 380 microM). GTP and GDP caused a 50% stimulation of the phospholipase C at 100 microM and at higher concentrations were inhibitory. The adenine nucleotides App[NH]p and ATP also caused small stimulatory effects (64% and 29%). The guanine nucleotide stimulation of inositide hydrolysis in cortical membranes was selective for inositol phospholipids over choline-containing phospholipids. Gpp[NH]p stimulated the production of inositol trisphosphate and inositol bisphosphate as well as inositol monophosphate, indicating that phosphoinositides are substrates for the phosphodiesterase. EGTA (33 microM) did not prevent the guanine nucleotide stimulation of inositide hydrolysis. Calcium addition by itself caused inositide phosphodiesterase activation from 3 to 100 microM which was additive with the Gpp[NH]p stimulation. These data suggest that guanine nucleotides may play a regulatory role in the modulation of the activity of phosphoinositide phosphodiesterase in rat cortical membranes.

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Phospholipase C-mediated hydrolysis of phosphatidylcholine is activated by muscarinic agonists

Biochemical Journal ◽

10.1042/bj2630115 ◽

1989 ◽

Vol 263 (1) ◽

pp. 115-120 ◽

Cited By ~ 27

Author(s):

M T Diaz-Meco ◽

P Larrodera ◽

M Lopez-Barahona ◽

M E Cornet ◽

P G Barreno ◽

...

Keyword(s):

Growth Factors ◽

Phospholipase C ◽

Guanine Nucleotide ◽

Muscarinic Agonists ◽

Guanine Nucleotide Binding Protein ◽

Permeabilized Cells ◽

Guanine Nucleotide Binding ◽

Oncogene Products ◽

Hydrolysis Of ◽

Stimulation Of

The phospholipase C-catalysed breakdown of inositol-containing phospholipids is an important source of diacylglycerol in cells stimulated by several agonists. However, recent experimental evidence suggests that major phospholipids such as phosphatidylcholine may also be substrates of the phosphodiesteratic hydrolysis activated by hormones, growth factors and oncogene products. We show here that stimulation of muscarinic agonists activates the release of phosphocholine, which, along with diacylglycerol, is a metabolic product of phospholipase C-mediated hydrolysis of phosphatidylcholine. Fluoroaluminates mimic this muscarinic effect, strongly suggesting that carbachol-activated release of phosphocholine may be mediated by a guanine-nucleotide-binding protein. Evidence for this was obtained from experiments using permeabilized cells in which non-hydrolysable analogues of GTP activated phosphocholine release synergistically with carbachol.

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GTP mobilization of Ca2+ from the endoplasmic reticulum of islets. Comparison with myo-inositol 1,4,5-trisphosphate

Biochemical Journal ◽

10.1042/bj2420137 ◽

1987 ◽

Vol 242 (1) ◽

pp. 137-141 ◽

Cited By ~ 27

Author(s):

B A Wolf ◽

J Florholmen ◽

J R Colca ◽

M L McDaniel

Keyword(s):

Endoplasmic Reticulum ◽

Additive Effect ◽

Guanine Nucleotide ◽

Rapid Release ◽

Inositol 1,4,5 Trisphosphate ◽

Hydrolysis Of

The effect of the guanine nucleotide GTP on Ca2+ release from the endoplasmic reticulum of digitonin-permeabilized islets was investigated. maximal and half-maximal Ca2+ release were observed at 5 microM- and 2.5 microM-GTP respectively. GTP caused a rapid release of Ca2+ from the endoplasmic reticulum, which was complete within 1 min. GTP-induced Ca2+ release was structurally specific and required the hydrolysis of GTP. The combination of maximal concentrations of GTP (10 microM) and myo-inositol 1,4,5-trisphosphate (IP3) (10 microM) resulted in an additive effect on Ca2+ release from the endoplasmic reticulum. GDP (100 microM), which inhibits GTP-induced Ca2+ release, did not affect IP3-induced Ca2+ release. Furthermore, GTP-induced Ca2+ release was not independent on submicromolar free Ca2+ concentrations, unlike IP3-induced Ca2+ release. These observations suggest that mechanistically GTP-induced Ca2+ release is different from IP3-induced Ca2+ release from the endoplasmic reticulum.

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Guanine nucleotide and NaF stimulation of phospholipase C activity in rat cerebral-cortical membranes. Studies on substrate specificity

Biochemical Journal ◽

10.1042/bj2440035 ◽

1987 ◽

Vol 244 (1) ◽

pp. 35-40 ◽

Cited By ~ 73

Author(s):

I Litosch

Keyword(s):

Substrate Specificity ◽

Phospholipase C ◽

Guanine Nucleotides ◽

Guanine Nucleotide ◽

Stimulatory Activity ◽

Maximal Activation ◽

Cortical Membranes ◽

Phosphatidylinositol 4 ◽

Hydrolysis Of ◽

Stimulation Of

Guanyl-5′-yl imidodiphosphate (p[NH]ppG) stimulated a rapid phospholipase C-mediated breakdown of exogenously added phosphatidylinositol 4,5-bisphosphate (PIP2) in rat cerebral-cortical membranes, with half-maximal activation at approx. 33 microM. NaF stimulated phospholipase C activity, with half-maximal activation at 0.5 mM. Stimulation of phospholipase C activity by NaF exhibited pH optima at approx. 5.5 and 7.0, with the stimulatory activity at pH 7.0 greater than that at pH 5.5. With p[NH]ppG, only stimulation at pH 7.0 was observed. Neither p[NH]ppG nor NaF stimulated hydrolysis of added phosphatidylinositol (PI) or phosphatidylinositol 4-phosphate (PIP). Mg2+ (0.5 mM) potentiated p[NH]ppG-stimulated breakdown of PIP2. Ca2+ increased basal and p[NH]ppG-stimulated breakdown of PIP2. PI breakdown was stimulated only by high Ca2+ concentrations and was unaffected by p[NH]ppG at any Ca2+ concentration examined. These results indicate that, in cerebral-cortical membranes, activation of phospholipase C by guanine nucleotides or fluoride directly increases a phospholipase C activity which specifically hydrolyses PIP2.

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Alpha 2-C10 adrenergic receptors expressed in rat 1 fibroblasts can regulate both adenylylcyclase and phospholipase D-mediated hydrolysis of phosphatidylcholine by interacting with pertussis toxin-sensitive guanine nucleotide-binding proteins.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)45856-5 ◽

1992 ◽

Vol 267 (4) ◽

pp. 2149-2156

Author(s):

E E MacNulty ◽

S J McClue ◽

I C Carr ◽

T Jess ◽

M J Wakelam ◽

...

Keyword(s):

Phospholipase D ◽

Pertussis Toxin ◽

Adrenergic Receptors ◽

Binding Proteins ◽

Nucleotide Binding ◽

Guanine Nucleotide ◽

Guanine Nucleotide Binding ◽

Nucleotide Binding Proteins ◽

Guanine Nucleotide Binding Proteins ◽

Hydrolysis Of

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Chemoattractant receptor-induced hydrolysis of phosphatidylinositol 4,5-bisphosphate in human polymorphonuclear leukocyte membranes. Requirement for a guanine nucleotide regulatory protein.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)88907-4 ◽

1985 ◽

Vol 260 (10) ◽

pp. 5875-5878 ◽

Cited By ~ 19

Author(s):

C D Smith ◽

B C Lane ◽

I Kusaka ◽

M W Verghese ◽

R Snyderman

Keyword(s):

Polymorphonuclear Leukocyte ◽

Regulatory Protein ◽

Guanine Nucleotide ◽

Human Polymorphonuclear Leukocyte ◽

Guanine Nucleotide Regulatory Protein ◽

Hydrolysis Of

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Role of a Guanine Nucleotide-Binding Regulatory Protein in the Hydrolysis of Phosphatidylinositol 4,5-Bisphosphate in a Human T Cell Line

Microbiology and Immunology ◽

10.1111/j.1348-0421.1988.tb01389.x ◽

1988 ◽

Vol 32 (3) ◽

pp. 293-304

Author(s):

Hiroko Hasegawa-Sasaki ◽

Frieder Lutz ◽

Terukatsu Sasaki

Keyword(s):

T Cell ◽

Cell Line ◽

Regulatory Protein ◽

Nucleotide Binding ◽

Guanine Nucleotide ◽

Human T Cell ◽

Guanine Nucleotide Binding ◽

Hydrolysis Of ◽

Human T Cell Line

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Guanine-nucleotide and hormone regulation of polyphosphoinositide phospholipase C activity of rat liver plasma membranes. Bivalent-cation and phospholipid requirements

Biochemical Journal ◽

10.1042/bj2480791 ◽

1987 ◽

Vol 248 (3) ◽

pp. 791-799 ◽

Cited By ~ 85

Author(s):

S J Taylor ◽

J H Exton

Keyword(s):

Phospholipase C ◽

Rat Liver ◽

Plasma Membranes ◽

Maximal Effect ◽

Guanine Nucleotide ◽

Guanine Nucleotide Binding Protein ◽

Liver Plasma Membranes ◽

Rat Liver Plasma Membranes ◽

Membrane Bound ◽

Hydrolysis Of

The effect of the GTP analogue guanosine 5′-[gamma-thio]triphosphate (GTP[S]) on the polyphosphoinositide phospholipase C (PLC) of rat liver was examined by using exogenous [3H]phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2]. GTP[S] stimulated the membrane-bound PLC up to 20-fold, with a half-maximal effect at approx. 100 nM. Stimulation was also observed with guanosine 5′-[beta gamma-imido]triphosphate, but not with adenosine 5′-[gamma-thio]triphosphate, and was inhibited by guanosine 5′-[beta-thio]diphosphate. Membrane-bound PLC was entirely Ca2+-dependent, and GTP[S] produced both a decrease in the Ca2+ requirement and an increase in activity at saturating [Ca2+]. The stimulatory action of GTP[S] required millimolar Mg2+. [8-arginine]Vasopressin (100 nM) stimulated the PLC activity approx. 2-fold in the presence of 10 nM-GTP[S], but had no effect in the absence of GTP[S] or at 1 microM-GTP[S]. The hydrolysis of PtdIns(4,5)P2 by membrane-bound PLC was increased when the substrate was mixed with phosphatidylethanolamine, phosphatidylcholine or various combinations of these with phosphatidylserine. With PtdIns(4,5)P2, alone or mixed with phosphatidylcholine, GTP[S] evoked little or no stimulation of the PLC activity. However, maximal stimulation by GTP[S] was observed in the presence of a 2-fold molar excess of phosphatidylserine or various combinations of phosphatidylethanolamine and phosphatidylserine. Hydrolysis of [3H]phosphatidylinositol 4-phosphate by membrane-bound PLC was also increased by GTP[S]. However, [3H]phosphatidylinositol was a poor substrate, and its hydrolysis was barely affected by GTP[S]. Cytosolic PtdIns(4,5)P2-PLC exhibited a Ca2+-dependence similar to that of the membrane-bound activity, but was unaffected by GTP[S]. It is concluded that rat liver plasma membranes possess a Ca2+-dependent polyphosphoinositide PLC that is activated by hormones and GTP analogues, depending on the Mg2+ concentration and phospholipid environment. It is proposed that GTP analogues and hormones, acting through a guanine nucleotide-binding protein, activate the enzyme mainly by lowering its Ca2+ requirement.

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Revisiting the Roco G-protein cycle

Biochemical Journal ◽

10.1042/bj20141095 ◽

2014 ◽

Vol 465 (1) ◽

pp. 139-147 ◽

Cited By ~ 20

Author(s):

Susanne Terheyden ◽

Franz Y. Ho ◽

Bernd K. Gilsbach ◽

Alfred Wittinghofer ◽

Arjan Kortholt

Keyword(s):

G Protein ◽

G Proteins ◽

Guanine Nucleotide Exchange Factors ◽

Guanine Nucleotide ◽

Nucleotide Exchange ◽

Guanine Nucleotide Exchange ◽

Nucleotide Exchange Factors ◽

Hydrolysis Of

Roco G-proteins have low nucleotide affinity and do not need helper proteins [guanine-nucleotide-exchange factors (GEFs)] to activate the protein. Roco proteins dimerize via the C-terminal of Roc (COR) domain, and efficient hydrolysis of active Roco–GTP to inactive Roco–GDP is dependent on dimerization of the G-domains.

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