Presence of guanine nucleotide-binding proteins in a plant hypocytyl microsomal fraction

Drøbak, Bjørn K.; Allan, Elizabeth; Comerford, J G; Roberts, Keith; Dawson, Alan P.

doi:10.1016/0006-291x(88)90713-9

Cited by 74 publications

(12 citation statements)

References 17 publications

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“…Though tempting as an hypothesis, our experiments do not necessarily indicate a trimeric G protein ) to be this nucleotide-sensitive site in the PLA2 response. Firstly, in this case, one would expect GTPTS alone to activate PLA2, as has been observed in animal systems (Murayama et al 1990;Narasimhan et al 1990;Teitelbaum 1990) and, secondly, one would not expect an effect of ADP since in plant membranes adenine nucleotides do not compete for GTP-binding sites very efficiently (Blum et al 1988;Droeback et al 1988;Jacobs et al 1990;Zbell et al 1989Zbell et al , 1990aPerdue and Lomax 1992). Only in membranes from Neurospora has binding of both GTP and ATP been observed, but the functional context remained unclear (Hasanuma 1991).…”

Section: Discussionmentioning

confidence: 81%

Stimulation of phospholipase A2 by auxin in microsomes from suspension-cultured soybean cells is receptor-mediated and influenced by nucleotides

Scherer

André

1993

Planta

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Abstract. The molecular mechanism of membrane-associated reactions induced by auxin was investigated in membranes isolated from cultured cells of soybean (Glycine max L.). Auxins increased the activity of phospholipase A 2 in microsomes isolated from suspensioncultured soybean cells. The reaction was measured as the accumulation of radioactive lysophosphatidylcholine hydrolyzed from radioactive phosphatidylcholine in membranes which had been prelabelled with [14-C]choline in vivo. Stimulation by auxin was detectable after 1 min and was auxin-specific in that weak auxins had little effect. Auxin concentrations as low as 2.10-SM and up to 2.10 3M ~-naphthaleneacetic acid already stimulated the phospholipase A 2 activity. Guanosine and adenosine diphosphate at 100 gM, if applied during homogenization of cells, completely abolished the stimulation of phospholipase A 2 by auxin and, when applied after homogenization, had no effect. Guanosine and adenosine 5'-O-thiotriphosphate, uridine 5'-diphosphate, and uridine 5'-triphosphate, all at 100 gM, had no effect in either treatment, suggesting that only nucleotides entrapped in the vesicles could exert an effect. The effect of auxin on phospholipase A2 had an optimum at pH 5.5 and was abolished completely by an antibody against the membrane-associated auxin-binding protein from maize coleoptiles, applied after homogenization. This antibody recognized a 22-kDa polypeptide in highly purified plasma membranes from cultured soybean cells. This suggests a receptor function for this auxin-binding protein and a role for a cytosolic nucleotide-binding protein in the activation of phospholipase A 2 by auxin. It is concluded that phospholipase A 2 has a function in plant signal transduction.Abbreviations: ABP = auxin-binding protein; ATP 7 S = adenosine 5'-O-thiotriphosphate; 2,4-D=2,4-dichlorophenoxyacetic acid; GYP 7 S --guanosine 5'-O-(thiotriphosphate); IgG = immunoglobulin G; LPC =lysophosphatidylcholine; ~-, fl-NAA = ~, fl-naphthaleneacetic acid; PLA 2 = phospholipase A 2

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Section: Discussionmentioning

confidence: 81%

Stimulation of phospholipase A2 by auxin in microsomes from suspension-cultured soybean cells is receptor-mediated and influenced by nucleotides

Scherer

André

1993

Planta

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“…Moreover, Western blot analysis of the microsomal fraction containing plasma membranes from R. tinctorum cells using this antibody showed the expected cross-reacting band of $ 42 kDa for Gaq/11. Mammalian antibodies have been earlier employed in several plant studies to identify different G-protein components of signalling systems (Drobak et al 1988, Wang et al 1993. Moreover, this antibody is raised against the region essential for binding to GTP, which is highly conserved throughout all alpha subunits from higher plant species sequenced and mammals (Assmann 2002).…”

Section: Fwtmentioning

confidence: 99%

Involvement of G‐proteins in chitosan‐induced Anthraquinone synthesis in Rubia tinctorum

Vasconsuelo

Picotto

Giuletti

et al. 2006

Physiologia Plantarum

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We have previously shown that chitosan stimulates anthraquinone synthesis in Rubia tinctorum L. cells through activation of the PLC/PKC, PI3K, MAPK and Ca 2þ messenger systems. In view of this evidence, we have now investigated whether guanine nucleotide-binding G-proteins are part of the signal transduction mechanism which mediates the elicitor action. The G-protein agonists mastoparan, AlF 4 -and GTPyS increased anthraquinone levels to the same extent as chitosan. No additive effects were observed when cultured R. tinctorum cells were treated with agonist and the elicitor together. In agreement with these observations, the G-protein antagonists suramin and GDPbS abolished the increase in anthraquinone synthesis induced by chitosan. Furthermore, elicitation was not affected in the presence of pertussis toxin. Consistent with this result, when cell cultures were preincubated with a monoclonal anti-Gaq/11 antibody, the chitosan-dependent increase in anthraquinone levels was fully inhibited. Moreover, the presence of an immunoreactive protein of the expected size for Gaq/11 (42 kDa) was observed in R. tinctorum microsomal membranes by Western blot analysis using the same antibody. These results indicate that chitosan stimulates anthraquinone synthesis in R. tinctorum cells through a heterotrimeric G-protein, most likely belonging to the Gaq family.

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“…GTP-binding activities and substrates for ADP ribosylation catalyzed by pertussis toxin were detected in gel filtration fractions of extracts from pea (Pisum sativum) and Lemna paucicostata [65][66][67]. In addition, a filter assay for GTP binding has been used to uncover small G proteins in the green alga Dunaliella salina [113,141], in microsomes of zucchini (Cucurbita pepo) hypocotyl [45 ], and in the chloroplast outer envelope membrane [148] and nuclear envelope from pea [29]. Furthermore, an ARF-like protein was detected in the cytosol of pea plumule cells [ 112].…”

Section: Detection Of Gtp-binding Proteinsmentioning

confidence: 99%

GTP-binding proteins in plants: new members of an old family

Mā

1994

Plant Mol Biol

199

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Regulatory guanine nucleotide-binding proteins (G proteins) have been studied extensively in animal and microbial organisms, and they are divided into the heterotrimeric and the small (monomeric) classes. Heterotrimeric G proteins are known to mediate signal responses in a variety of pathways in animals and simple eukaryotes, while small G proteins perform diverse functions including signal transduction, secretion, and regulation of cytoskeleton. In recent years, biochemical analyses have produced a large amount of information on the presence and possible functions of G proteins in plants. Further, molecular cloning has clearly demonstrated that plants have both heterotrimeric and small G proteins. Although the functions of the plant heterotrimeric G proteins are yet to be determined, expression analysis of an Arabidopsis G alpha protein suggests that it may be involved in the regulation of cell division and differentiation. In contrast to the very few genes cloned thus far that encode heterotrimeric G proteins in plants, a large number of small G proteins have been identified by molecular cloning from various plants. In addition, several plant small G proteins have been shown to be functional homologues of their counterparts in animals and yeasts. Future studies using a number of approaches are likely to yield insights into the role plant G proteins play.

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Presence of guanine nucleotide-binding proteins in a plant hypocytyl microsomal fraction

Cited by 74 publications

References 17 publications

Stimulation of phospholipase A2 by auxin in microsomes from suspension-cultured soybean cells is receptor-mediated and influenced by nucleotides

Stimulation of phospholipase A2 by auxin in microsomes from suspension-cultured soybean cells is receptor-mediated and influenced by nucleotides

Involvement of G‐proteins in chitosan‐induced Anthraquinone synthesis in Rubia tinctorum

GTP-binding proteins in plants: new members of an old family

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