Naphthylphthalamic acid-binding sites in cultured cells from Nicotiana tabacum

Naphthylphthalamic acid-binding sites in cultured cells from Nicotiana tabacum

Naphthylphthalamic acid (NPA), an inhibitor of polar auxin transport, binds with high affinity to membrane preparations from callus and cell suspension cultures derived from Nicotiana tabacum (Kd approx. 2·10-9 M). The concentration of membrane-bound binding sites is higher in cell suspension than i...

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Bibliographic Details
Published in:Planta Vol. 164; no. 1; pp. 69 - 74
Main Authors: Maan, A.C, Kuhnel, B, Beukers, J.J.B, Libbenga, K.R
Format: Journal Article
Language:English
Published: Berlin Springer-Verlag 01-01-1985
Springer
Subjects:
Auxins
Binding sites
Biological and medical sciences
Callus
cell culture
Cell receptors
Cell structures and functions
Chemical suspensions
Corn
Cultured cells
Fundamental and applied biological sciences. Psychology
Indoleacetic acids
Ligands
Molecular and cellular biology
Nicotiana tabacum
Receptors
Cell culture
Callus
Auxin
Tissue culture
Binding site
Nicotiana tabacum
Suspension culture
Membrane receptor
Dicotyledones
Angiospermae
Membrane
Plant growth substance
Spermatophyta
Solanaceae
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Summary:Naphthylphthalamic acid (NPA), an inhibitor of polar auxin transport, binds with high affinity to membrane preparations from callus and cell suspension cultures derived from Nicotiana tabacum (Kd approx. 2·10-9 M). The concentration of membrane-bound binding sites is higher in cell suspension than in callus cultures. The binding of NPA to these sites seems to be a simple process, in contrast to the binding of the synthetic auxin naphthylacetic acid (1-NAA) to membrane preparations from callus cultures, which is more complex (A.C. Maan et al., 1983, Planta 158, 10—15). Naphthylacetic acid, a number of structurally related compounds and the auxin-transport inhibitor triiodobenzoic acid were all able to compete with NPA for the same binding site with Kd values ranging from 10-6 to 10-4 M. On the other hand, NPA was not able to displace detectable amounts of NAA from the NAA-binding site. A possible explanation is the existence of two different membrane-bound binding sites, one exclusively for auxins and one for NPA as well as auxins, that differ in concentration. The NPA-binding site is probably an auxin carrier.
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ISSN:0032-0935
1432-2048
DOI:10.1007/BF00391027