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We studied the possible use of the detergent Brij 58 in physiological experiments for the reorientation of right-side-out plasmalemmal vesicles, which were isolated from wheat ( Triticum aestivum L.) coleoptiles. The activities of K+, Mg2+-ATPase and the ATP-dependent H+-potential were higher in Brij 58-treated vesicles, whereas membrane permeability for K+ and Na+ remained unchanged. Brij 58 did not suppress the ATP-dependent IAA transport into vesicles and RNA polymerase II activation by IAA–protein plasmalemmal complexes in the system of isolated nuclei. The conclusion was that, using Brij 58, we could obtain the plasmalemmal fraction, which consisted almost completely of closed inverted vesicles. These vesicles can be applied for the in vitro study of the processes, which occur on the cytosolic plasmalemmal surface. [ABSTRACT FROM AUTHOR]

The changes in the specific binding of 3H-IAA to the plasmalemma from segments of wheat ( Triticum aestivumL.) coleoptiles and the physiological activity of the IAA–protein complexes thus formed in dependence on the duration of gravitational stimulation (GS) (1 g) were studied. The overall inhibition of the formation of IAA–protein complexes was accompanied by a transverse polarization of their functional activity occurring as early as within two minutes after the onset of GS. The pretreatment of plasmalemmal vesicles with 0.1 μM CaCl2prevented the in vitroIAA–protein complex formation in the plasmalemma. It is suggested that the GS results in an increase in the plasmalemma permeability for Ca2+, which reduces the capacity of the plasmalemma to bind IAA at the early stages of the gravitropic response. [ABSTRACT FROM AUTHOR]