Biochemistry and molecular biology of binding proteins for plant growth regulators.
type: CreativeWork
description: Plant growth regulators have a vital role in plant growth and development. The cellular response to these regulators depends on the presence and the action of specific receptors. The plant growth regulators and their receptors act together in complexes which determine the final effects of the plant growth regulators. In the research reported here, emphasis has been given to the regulation of the activity of the receptors themselves. The regulation of the N-l-naphthylphthalamic acid (N~A) receptor through phosphorylation and dephosphorylation and the regulation of the auxin binding protein (ABP) through gene manipulation have been investigated. NPA, an auxin transport inhibitor, was found to bind specifically to a crude membrane preparation from sugar beet seedling leaf cell suspension cultures. The in vitro binding was optimal at pH 4.5 and 4?C. Binding parameters for NP A binding were determined by Scatchard analysis. The dissociation constant (Kd) and binding protein concentration were found to be 1.71 x 10-7 mol dm-3 and 220 pmoles g-I membrane protein respectively. It was found that the amount of specific 3H-NPA binding was significantly increased by adding Mg2+ A TP to the binding assay solution; treatment of membrane preparations with acid phosphatase, prior to the NP A binding assay, resulted in lower specific binding. A TP activation and phosphatase inactivation were culture stage dependent. Although a considerable effect could be detected when using cells from day 8 (representing the linear phase), the same treatment did not alter the binding if cells from day I (representing lag phase) or day 14 (representing the stationary phase) were used. These observations have strongly highlighted the possible involvement of a phosphorylation and dephosphorylation mechanism in vivo in the regulation of the activity of the NP A receptor. High phosphatase activity was found in the supernatant, but not in the membrane pellet, after 50,000 g centrifugation. The presence o…
abstract: Plant growth regulators have a vital role in plant growth and development. The cellular response to these regulators depends on the presence and the action of specific receptors. The plant growth regulators and their receptors act together in complexes which determine the final effects of the plant growth regulators. In the research reported here, emphasis has been given to the regulation of the activity of the receptors themselves. The regulation of the N-l-naphthylphthalamic acid (N~A) receptor through phosphorylation and dephosphorylation and the regulation of the auxin binding protein (ABP) through gene manipulation have been investigated. NPA, an auxin transport inhibitor, was found to bind specifically to a crude membrane preparation from sugar beet seedling leaf cell suspension cultures. The in vitro binding was optimal at pH 4.5 and 4?C. Binding parameters for NP A binding were determined by Scatchard analysis. The dissociation constant (Kd) and binding protein concentration were found to be 1.71 x 10-7 mol dm-3 and 220 pmoles g-I membrane protein respectively. It was found that the amount of specific 3H-NPA binding was significantly increased by adding Mg2+ A TP to the binding assay solution; treatment of membrane preparations with acid phosphatase, prior to the NP A binding assay, resulted in lower specific binding. A TP activation and phosphatase inactivation were culture stage dependent. Although a considerable effect could be detected when using cells from day 8 (representing the linear phase), the same treatment did not alter the binding if cells from day I (representing lag phase) or day 14 (representing the stationary phase) were used. These observations have strongly highlighted the possible involvement of a phosphorylation and dephosphorylation mechanism in vivo in the regulation of the activity of the NP A receptor. High phosphatase activity was found in the supernatant, but not in the membrane pellet, after 50,000 g centrifugation. The presence o…
author: Zhang, Yun-Heng
license: https://dora.dmu.ac.uk/bitstreams/bac29528-4891-4ab0-9918-d97d1183540d/download
date published: 2000
date modified: 2026-07-24T06:18:31Z
provider: De Montfort University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: De Montfort University