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Vis Neurosci. 1993 May-Jun;10(3):473-8.

Identification of a G-protein in depolarizing rod bipolar cells.

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Department of Anatomy, University of Pennsylvania, Philadelphia 19104-6058.


Synaptic transmission from photoreceptors to depolarizing bipolar cells is mediated by the APB glutamate receptor. This receptor apparently is coupled to a G-protein which activates cGMP-phosphodiesterase to modulate cGMP levels and thus a cGMP-gated cation channel. We attempted to localize this system immunocytochemically using antibodies to various components of the rod phototransduction cascade, including Gt (transducin), phosphodiesterase, the cGMP-gated channel, and arrestin. All of these antibodies reacted strongly with rods, but none reacted with bipolar cells. Antibodies to a different G-protein, G(o), reacted strongly with rod bipolar cells of three mammalian species (which are depolarizing and APB-sensitive). Also stained were subpopulations of cone bipolar cells but not the major depolarizing type in cat (b1). G(o) antibody also stained certain salamander bipolar cells. Thus, across a wide range of species, G(o) is present in retinal bipolar cells, and at least some of these are depolarizing and APB-sensitive.

[Indexed for MEDLINE]

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