Résumé
The nature of the G-proteins present in the pre- and post-synaptic plasma membranes and in the synaptic vesicles of cholinergic nerve terminals purified from the
Torpedo electric organ was investigated. In pre- and post-synaptic plasma membranes,
Bordetella pertussis toxin, known to catalyze the ADP-ribosylation of the α-subunit of several G-proteins, labels two substrates at 41 and 39 kDa. The 39 kDa subunit detected by ADP-ribosylation in the synaptic plasma membrane fractions was immunologically similar to the G
o α-subunit purified from calf brain. In contrast to bovine chromaffin cell granules, no G-protein could be detected in
Torpedo synaptic vesicles either by ADP-ribosylation or by immunoblotting.