J. Valat et al., IMMUNOCYTOCHEMICAL LOCALIZATION OF THE GTP-BINDING PROTEIN G(0)-ALPHAIN THE VESTIBULAR EPITHELIUM AND GANGLION OF THE GUINEA-PIG, Journal of neurocytology, 24(12), 1995, pp. 916-924
The guanine nucleotide binding protein Go alpha was immunolocalized in
the guinea-pig vestibular system by confocal and electron microscopy.
The vestibular sensory epithelia consist of the macula utriculi, macu
la sacculi and cristae ampullaris of the semicircular canals. Two type
s of hair cells are present in these epithelia. Type I hair cells are
surrounded by an afferent nerve calyx that receives efferent innervati
on and type IT hair cells are innervated directly by the afferent and
efferent nerves. Go alpha protein was observed on the inner face of th
e afferent calyceal membrane surrounding type I hair cells and in nerv
e endings in contact with type II hair cells. No labelling was found i
n the stereocilia and cuticular plate of type I and type II hair cells
whereas the cytoplasmic matrix displayed a diffuse labelling. The pla
sma membrane of the supporting cells showed discreet labelling in the
confocal microscope that are still confirmed by electron microscopy. A
positive reaction was also observed along the plasma membrane of the
vestibular ganglion neurons. Immunoblotting with affinity-purified pol
yclonal rabbit antibodies selective for the 39 kDa alpha subunit of G(
o) indicated that G(o) alpha protein was present in both the vestibula
r ganglion. That G(o) alpha labelling was observed in the cytoplasm of
vestibular hair cells and in nerve endings contacting hair cells sugg
ests that G(o) may be involved in the modulation of vestibular neurotr
ansmission.