Localization of G-protein in rat occipital cerebral cortex

Localization of guanine nucleotide-binding regulatory protein (G-protein) was investigated in occipital cerebral cortical tissue of rat. An immunofluorescence histochemical staining technique was employed using a rabbit polyclonal antibody raised against bovine brain G-protein. Fluorescent staining was primarily localized to neurons, and labelled the cell body and the proximal region of processes. It appeared that all neuronal cells were equally stained, at least in layers II-VI where cell density permitted a direct assessment. The possibility of synaptic labelling could not be eliminated; however, no significant staining of glial elements was detected. The specific nature of staining was supported on Western blots of cortical extract, where the antibody recognized essentially two bands which coelectrophoresed with the alpha- and beta-subunits of purified G-protein. These results suggest that one potential role for the major species of G-protein present in cerebral cortex (Go) may be the overall regulation of neuronal activity.