Distinct cellular expression of pertussis toxin-sensitive GTP-binding proteins in rat cerebellum

Immunohistochemical localization of pertussis toxin-sensitive GTP-binding proteins in rat cerebellum was investigated using antibodies raised against purified G alpha o and synthetic peptides corresponding to specific sequences of G alpha i1, G alpha i2 and G alpha o was detected mostly in the molecular layer but not in the cell body of the Purkinje cells. G alpha i1 and G alpha i2 were found predominantly in the molecular layer and in addition in the cell body of the Purkinje cells. G alpha i3 was not detected in rat cerebellum. Immunoblot analysis demonstrated that in the cerebellum membrane G alpha 0 was most abundant and surprisingly the amount of G alpha i2 was much higher than that of G alpha i1. Thus, each pertussis toxin substrate was found to be expressed differently in rat cerebellum. The different patterns of expression imply that each subtype of GTP-binding proteins may have a specific function in modulating the neuronal activity in rat cerebellum.