POSTTRANSLATIONAL MODIFICATIONS OF TUBULIN SUGGEST THAT DYNAMIC MICROTUBULES ARE PRESENT IN SENSORY CELLS AND STABLE MICROTUBULES ARE PRESENT IN SUPPORTING CELLS OF THE MAMMALIAN COCHLEA
Nb. Slepecky et al., POSTTRANSLATIONAL MODIFICATIONS OF TUBULIN SUGGEST THAT DYNAMIC MICROTUBULES ARE PRESENT IN SENSORY CELLS AND STABLE MICROTUBULES ARE PRESENT IN SUPPORTING CELLS OF THE MAMMALIAN COCHLEA, Hearing research, 91(1-2), 1995, pp. 136-147
Post-translational modifications to tubulin in the sensory and support
ing cells of the cochlea were studied using antibodies specific to the
tyrosinated, detyrosinated, acetylated and polyglutamylated isoforms.
In the sensory cells, microtubules which label intensely with antibod
ies to tyrosinated tubulin are found in networks within the cytoplasm.
Microtubules which label with antibodies to detyrosinated tubulin and
polyglutamylated tubulin, but not acetylated tubulin, form a small co
mponent of the microtubules found in the cytoplasm only in the region
below the cuticular plate. Microtubules in the supporting cells (inner
and outer pillar cells and Deiters cells) are arranged in bundles and
contain little tyrosinated tubulin. They are composed instead of pred
ominantly post-translationally modified isoforms which include detyros
inated, acetylated and polyglutamylated tubulin. The findings suggest
that microtubules in the sensory cells form dynamic structures, since
microtubules that undergo cyclic polymerization and depolymerization p
redominantly contain tubulin that has not yet had its carboxy-terminal
tyrosine residue removed. The presence of microtubules in the support
ing cells in which the tubulin has been polymerized into microtubules
long enough to be post-translationally modified, provides evidence tha
t these microtubules are stable, long-lived and could contribute to th
e structural support of the sensory organ of Corti.