ISSN:
1615-6102
Keywords:
Binding sites
;
Cell culture
;
Cytokinin
;
Daucus carota
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary Carrot suspension cells contain one class of high affinity binding sites for cytokinin in an 80,000 × g particulate fraction. Binding of [8-14C]-benzylaminopurine (BA) to this fraction assayed by a sedimentation method was found to be optimal at pH 6.0 and thermolabile. Specific binding was proved in competition experiments in which labelled BA was displaced by increasing concentrations of unlabelled BA. Scatchard plots of these results displayed a dissociation constant (Kd) of 33 ± 6 nM. The number of binding sites found was 1,100 ± 120 fmol g−1 fresh weight which is equivalent to a frequency of 23,000 binding sites per cell. The specificity of the binding sites to cytokinins and their analogues followed the sequence BA with highest affinity, kinetin, zeatin, iP and adenine. The cytokinin ribosides generally had a lower affinity than their cytokinin bases, and the affinity decreased in the order [9 R] BA, [9 R] iP, [9 R] Z, [9 R] A.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02115968
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