Disturbing gtp-binding protein function through microinjection into the visual cell of limulus

Abstract

We have tested the action of three agents microinjected into the ventral nerve photoreceptor of Limulus on the electrical response to dim light. 1. A monoclonal antibody (mAb 4A) against the Gα subunit of frog transducin reduces the size of the receptor current to 60%, suggesting an interaction with Gα in the Limulus photoreceptor. 2. Injection of Clostridium botulinum ADPribosyltransferase C 3 reduces the size to 46%; latency is not affected. The results imply that small GTP-binding proteins play a functional role in photoreception of invertebrates. 3. Injection of GDP-ß-S reduces dose-dependently the size of the receptor current to 15% and prolongs the latency to 200%, presumably by reducing number and rate of G-protein activations. © 1992, Walter de Gruyter. All rights reserved.