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. 1989 Nov;91(3):823–828. doi: 10.1104/pp.91.3.823

Competition for in Vitro [3H]Gibberellin A4 Binding in Cucumber by Substituted Phthalimides

Comparison with in Vivo Gibberellin-Like Activity

Nasser Yalpani 1,2,1, Jeffrey C Suttle 1,2, Julie F Hultstrand 1,2, Shirley J Rodaway 1,2
PMCID: PMC1062082  PMID: 16667143

Abstract

Certain N-substituted phthalimides (NSPs) have gibberellin (GA)-like activity in a number of GA bioassays. The interaction between representative NSPs and a protein fraction from cucumber (Cucumis sativus L.) hypocotyls that has GA-binding characteristics consistent with those expected of GA receptors was studied. Analysis of in vitro equilibrium saturation data indicated the presence of only one class of high affinity [3H]GA4 binding sites (Kd ∼ 30 nanomolar, n = 0.25 picomole per milligram of protein). In the presence of 6 or 60 micromolar 1-[3-chlorophthalimido]-cyclohexanecarboximide (AC-94,377), the Kd for [3H]GA4 increased, whereas the maximum number of saturable [3H]GA4 binding sites did not change significantly. The dissociation of [3H]GA4 from its binding sites was complex and was best described by a bi-exponential equation. AC-94,377 did not affect the rates of [3H]GA4 dissociation from its binding sites. These results implied that AC-94,377 and [3H]GA4 compete for binding to the same sites. A correlation was observed between the activity of over 20 NSPs in the cucumber hypocotyl bioassay and their in vitro affinity for the GA binding sites. Our observations lend further support to the notion that certain GA binding proteins in cucumber cytosol are GA receptors and also provide a molecular explanation for the GA-like in vivo activity of some NSPs.

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Selected References

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  1. Hughes J., Smith T., Morgan B., Fothergill L. Purification and properties of enkephalin - the possible endogenous ligand for the morphine receptor. Life Sci. 1975 Jun 15;16(12):1753–1758. doi: 10.1016/0024-3205(75)90268-4. [DOI] [PubMed] [Google Scholar]
  2. Keith B., Brown S., Srivastava L. M. In vitro binding of gibberellin A(4) to extracts of cucumber measured by using DEAE-cellulose filters. Proc Natl Acad Sci U S A. 1982 Mar;79(5):1515–1519. doi: 10.1073/pnas.79.5.1515. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Laduron P. M. Stereospecificity in binding studies. A useful criterion though insufficient to prove the presence of receptors. Biochem Pharmacol. 1988 Jan 1;37(1):37–40. doi: 10.1016/0006-2952(88)90752-6. [DOI] [PubMed] [Google Scholar]
  4. Munson P. J., Rodbard D. Ligand: a versatile computerized approach for characterization of ligand-binding systems. Anal Biochem. 1980 Sep 1;107(1):220–239. doi: 10.1016/0003-2697(80)90515-1. [DOI] [PubMed] [Google Scholar]
  5. Reynolds I. J., Snowman A. M., Snyder S. H. (-)-[3H] desmethoxyverapamil labels multiple calcium channel modulator receptors in brain and skeletal muscle membranes: differentiation by temperature and dihydropyridines. J Pharmacol Exp Ther. 1986 Jun;237(3):731–738. [PubMed] [Google Scholar]
  6. Suttle J. C., Hultstrand J. F. Physiological Studies of a Synthetic Gibberellin-Like Bioregulator: II. Effect of Site of Application on Biological Activity. Plant Physiol. 1987 Aug;84(4):1068–1073. doi: 10.1104/pp.84.4.1068. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Wing K. D., Slawecki R. A., Carlson G. R. RH 5849, a Nonsteroidal Ecdysone Agonist: Effects on Larval Lepidoptera. Science. 1988 Jul 22;241(4864):470–472. doi: 10.1126/science.241.4864.470. [DOI] [PubMed] [Google Scholar]
  8. Yalpani N., Srivastava L. M. Competition for in vitro [h]gibberellin a(4) binding in cucumber by gibberellins and their derivatives. Plant Physiol. 1985 Dec;79(4):963–967. doi: 10.1104/pp.79.4.963. [DOI] [PMC free article] [PubMed] [Google Scholar]

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