2010 - Electrophysiological characterization of ATPases in native synaptic vesicles and synaptic plasma membranes

Icon N1   SURFE²R ONE (a predecessor model of SURFE²R N1) publication in Biochemical Journal (2010)

Obrdlik P., Diekert K., Watzke N., Keipert C., Pehl U., Brosch C., Boehm N., Bick I., Ruitenberg M., Volknandt W., Kelety B.

Biochemical Journal (2010) 427(1):151-159


Vesicular V-ATPase (V-type H+-ATPase) and the plasma membrane-bound Na+/K+-ATPase are essential for the cycling of neurotransmitters at the synapse, but direct functional studies on their action in native surroundings are limited due to the poor accessibility via standard electrophysiological equipment. We performed SSM (solid supported membrane)-based electrophysiological analyses of synaptic vesicles and plasma membranes prepared from rat brains by sucrose-gradient fractionation. Acidification experiments revealed V-ATPase activity in fractions containing the vesicles but not in the plasma membrane fractions. For the SSM-based electrical measurements, the ATPases were activated by ATP concentration jumps. In vesicles, ATP-induced currents were inhibited by the V-ATPase-specific inhibitor BafA1 (bafilomycin A1) and by DIDS (4,4'-di-isothiocyanostilbene-2,2'-disulfonate). In plasma membranes, the currents were inhibited by the Na+/K+-ATPase inhibitor digitoxigenin. The distribution of the V-ATPase- and Na+/K+-ATPase-specific currents correlated with the distribution of vesicles and plasma membranes in the sucrose gradient. V-ATPase-specific currents depended on ATP with a K0.5 of 51+/-7 microM and were inhibited by ADP in a negatively co-operative manner with an IC50 of 1.2+/-0.6 microM. Activation of V-ATPase had stimulating effects on the chloride conductance in the vesicles. Low micromolar concentrations of DIDS fully inhibited the V-ATPase activity, whereas the chloride conductance was only partially affected. In contrast, NPPB [5-nitro-2-(3-phenylpropylamino)-benzoic acid] inhibited the chloride conductance but not the V-ATPase. The results presented describe electrical characteristics of synaptic V-ATPase and Na+/K+-ATPase in their native surroundings, and demonstrate the feasibility of the method for electrophysiological studies of transport proteins in native intracellular compartments and plasma membranes.

Download here


We use cookies on our website. Some of them are essential for the operation of the site, while others help us to improve this site and the user experience (tracking cookies). You can decide for yourself whether you want to allow cookies or not. Please note that if you reject them, you may not be able to use all the functionalities of the site.