ULTRASTRUCTURAL-LOCALIZATION OF G-PROTEIN G(S) IN THE LATERAL WALL OFTHE GUINEA-PIG COCHLEAR DUCT

Immunocytochemical localization of a GTP-binding protein, G(s), in the various cells of the-lateral wall of guinea pig cochlear duct was inv estigated using a post-embedding immunogold method with antibody raise d against a synthetic decapeptide (RMHLRQYELL) encoding the C-terminus of the alpha-subunit of G(s). In the stria vascularis, labeling was o bserved on the basolateral membrane infoldings of marginal cells, on t he juxtaposed membrane of intermediate cells, and on the cell membrane of basal cell. In contrast, no significant labeling was observed on t he luminal membrane of marginal cells. Immunoreactivity also was detec ted on the cell membranes of various other cells. These include spiral prominence epithelial cells, fibrocytes of spiral ligament, external sulcus cells, and epithelial and mesothelial cells of Reissner's membr ane. Adenylylcyclase has been functionally implicated in some of the c ell types with membranes labeled in this study. The significance of th ese findings is briefly discussed.