Chemistry Reference
In-Depth Information
of the brain through its effect on voltage-gated calcium channels as well as on NMDA,
-aminobutyric acid
(GABA), glycine, nicotinic, dopaminergic, and serotonin receptors (
Figure 20.10
)
. The zinc which has been stored
g
FIGURE 20.10
Zinc trafficking at the gluzinergic synapse. Zinc enters synaptic vesicles of gluzinergic terminals via the zinc transporter
(ZnT-3) and is stored with glutamate. During normal stimulation, zinc is released along with glutamate into the synaptic cleft where it can then
act on postsynaptic channel proteins such as GABA receptors, NMDA receptors, voltage-gated channels, or a number of other ion channels to
alter their activity, many of which have not been well defined; e.g., the unknown channel illustrated on the glial cell membrane (question mark).
Metallothioneins (MTs) are primary intracellular zinc-buffering proteins and they regulate the availability of free zinc in presynaptic terminals
and postsynaptic neurons. The metallothionein molecule (inset) consists of two domains, in each of which zinc is bound in a cluster. In one
domain, three zinc atoms are bound to nine cysteines (cys), whereas in the other domain, four zinc atoms are bound to eleven cysteines. Each
zinc atom is tetrahedrally coordinated to four thiolate bonds with some of the thiolate ligands sharing the zinc atom.
(From
Bitanihirwe &
Cunningham, 2009
. Copyright 2009 with permission from John Wiley and Sons.)
together with glutamate in the synaptic vesicles is released during normal stimulation, together with glutamate
into the synaptic cleft. There, it can act on postsynaptic channel proteins, such as GABA receptors, NMDA
receptors, voltage-gated channels, or a number of other ion channels to alter their activity. Metallothioneins are the
primary intracellular buffering proteins, and they regulate the availability of free zinc in presynaptic terminals and
postsynaptic neurons. The metallothionein molecule (
Figure 20.10
)
consists of two domains, in each of which zinc
is bound in a cluster. In one domain, three zinc atoms are bound to nine cysteines (cys), whereas in the other
domain, four zinc atoms are bound to eleven cysteines. Each zinc atom is tetrahedrally coordinated to four thiolate
bonds, with some of the thiolate ligands sharing the zinc atom.
