ULTRASTRUCTURAL-LOCALIZATION OF G-PROTEIN G(S) IN THE ORGAN OF CORTI

Immunocytochemical localization of a stimulatory GTP-binding protein G (s) in the organ of Corti in the inner ear was examined with a post-em bedding immunogold technique, using antibodies raised against a synthe tic decapeptide (RIMHLRQYELL) of the C-terminus of the a subunit of G( s). Immunoreactivity was strong on the membranes of supporting cells i n the reticular lamina, including inner and outer pillar cells and the phalangeal process of Deiters' cells. Immunolabeling also was seen on the membranes of cell bodies of those cells which surround nerve fibe rs, basilar fibers, outer spiral fibers and afferent nerve endings at outer hair cells. Gold particles also labeled the membrane of inner ph alangeal cells and border cells. In contrast, outer and inner hair cel ls were not labeled. Possible roles of G(s) in the organ of Corti are discussed.