Lecture 37: GABA Signaling Flashcards
What are the substrates for the GABA-T (GABA alpha-ketoglutarate transaminase) reaction?
Gamma-Amino Butyrate
Succinic semialdehyde
What are the products of the GABA-T (GABA alpha-ketoglutarate transaminase) reaction?
alpha-ketoglutarate
Glutamate
What are the substrates and products for the SSADH (succinic semialdehyde dehydrogenase) reaction?
Substrates: Succinic semialdehyde, NAD
Products: Succinate, NADH+
What is the function of the central pore on the GABA-A receptor?
Allows for ion (Cl-) conductance
PLGICs
Pentameric Ligand Gated Ion Channels; superfamily of proteins that only opens in presence of ligand (GABA); needs 5 subunits
Where do drugs and GABA bind on the GABA-A receptor?
N terminus
Describe the structure of one subunit on the GABA-A receptor
N terminus is most of molecule projected extracellularly
4 transmembrane helices
Large cytoplasmic loop which is dynamic
(5 of these come together)
Where specifically does GABA bind to the GABA-A receptor?
At the interface between the alpha and beta subunits
Where do benzodiazepines bind to GABA-A receptor?
At the interface between the alpha and gamma subunits
phasic inhibition
Happens in synapse; GABA binds to receptor and “quiets” target cell - dependent on release of neurotransmitter
tonic inhibition
Extrasynaptic; neurotransmitter receptors are “speckled” throughout surface of neuron; neurons are “bathed” with certain level of escaped GABA which has an effect on “speckled receptors”
How is the glycine receptor (a member of the PLGIC superfamily) different from the GABA-A receptor?
More poorly understood and distributed, anchored to cytoskeleton by gephyrin
What enzyme catalyzes the conversion of Glutamate to CO2 and gamma-amino butyrate?
GAD (Glutamic acid decarboxylase)
