Abscisic acid bound

Matthyssee and Phillips (20) isolated two nuclear proteins, from tobacco cells, that bound specifically to 2,4-D. Receptor proteins for auxins, kinetins, and GA have been found (21). Sub-cellular fractions from bean leaves were recently shown to bind abscisic acid (22). Preliminary experiments (22) indicated that maximum ABA binding activity coincides with the activities of membrane-bound Mg -dependent, K+-stimulated ATPase and glucan synthetase. Table I of Biswas and Roy (21) lists hormone receptor proteins reported in plant tissue. For a protein to qualify as a receptor molecule, it should have a high stereo-specific binding capacity (Kd 10 6 to 10 SM) for its particular hormone. In com coleoptiles, both IAA and NAA are equally effective in inducing cell elongations fractions of plasma membrane and endoplasmic reticular membrane contain receptor proteins with Kd values of 10 M to 10 M for auxins (5, 18). When one considers procedural... 

Effects on Abscisic Acid and Cytokinins. Lepage-Digivry (1973) reported an increase in bound ABA at the expense of free ABA in seeds of Taxus baccata during stratification. Enu-Kwesi and Dumbroff (1977) also reported a cold-induced reduction in detectable ABA in Acer fruits but, in most cases, changes in ABA levels have not shown a close correlation with thermodormancy (Berrie and Robertson 1976). 

---