Ultrastructural Localization of the G-protein G_s in the Dark Cells of Rat Vestibular Organs

Abstract

Immunocytochemical localization of the GTP-binding protein G_s in the rat vestibular organs was investigated using a post-embedding immunogold method with an antibody raised against the C-terminus of the α-subunit of G_s. In the crista ampullaris and the utricle, labeling was detected on the deeply infolded basolateral membrane of the dark cells, but not on the luminal membrane. No labeling was detected on transitional cells or on wall cells facing the endolymph. The present observation provides a detail of hormonal regulation of vestibular organs, which in turn regulate ion transport and fluid homeostasis in the vestibular endolymph.