Neurotransmitters
Name the three criteria that must be met for a substance to be defined as a neurotransmitter.
1. Present in presynaptic neuron
2. Released in response to depolarization (Ca²⁺ dependent)
3. Specific receptors exist on postsynaptic cell
Which type of signaling involves hormones traveling through the circulatory system to distant cells?
Endocrine signaling.
The enzyme _______ is responsible for the synthesis of cAMP.
Adenylyl cyclase
How many transmembrane domains typically make up a G-protein coupled receptor (GPCR)?
7
Myasthenia Gravis is an autoimmune disorder caused by antibodies blocking which receptors?
Nicotinic Acetylcholine Receptors (nAChR)
Which neurotransmitter is the most prevalent excitatory transmitter in the brain?
Glutamate
Describe the main difference between ionotropic and metabotropic receptors.
Ionotropic receptors are ligand-gated ion channels (fast)
Metabotropic receptors are G-protein coupled (slow/indirect).
Phospholipase C (PLC) cleaves membrane lipids to produce two second messengers: _______ and IP3.
Diacylglycerol (DAG)
Name the family of scaffolding proteins that function at the postsynaptic density of excitatory synapses.
PSD-95 family (or MAGUKs)
What is the rate-limiting enzyme in the synthesis of all catecholamines?
Tyrosine Hydroxylase (TH)
In the adult brain, GABA is the primary ________ neurotransmitter.
Heterotrimeric G-proteins are "on" or active when they are bound to which molecule?
GTP (Guanosine triphosphate)
What are the two primary pharmacologically different calcium stores found in the Endoplasmic Reticulum (ER)?
IP3 receptors and Ryanodine receptors
The first two PDZ domains of PSD-95 primarily interact with the C-terminus of which receptor?
NMDA Receptors
Sarin and Soman are nerve gases that act as irreversible inhibitors of the enzyme ________.
Acetylcholinesterase (AChE)
Which amino acid is the direct precursor for the synthesis of GABA & which enzyme facilitates this conversion?
Glutamate; glutamate decarboxylase (GAD)
Explain the concept of "signal amplification" in G-protein cascades.
A single signal molecule can activate multiple G-proteins, each activating enzymes that produce thousands of second messengers, leading to a massive exponential response.
_______ is a gaseous retrograde messenger that stimulates the synthesis of cGMP.
Nitric Oxide (NO)
Describe the function of Shank proteins at the postsynaptic density.
They are scaffold proteins that connect receptors and ion channels to the actin cytoskeleton and G-protein signaling pathways.
Why does GABA act as an excitatory neurotransmitter in the developing brain but an inhibitory one in the mature brain?
In developing neurons, high intracellular Cl⁻ (due to Na⁺/K⁺/Cl⁻ co-transporter) makes Cl⁻ flow out when GABA channels open, causing depolarization
In adults, Cl⁻ is pumped out, making the reversal potential more negative.
Name the three catecholamine neurotransmitters.
Dopamine, Norepinephrine, Epinephrine
The NMDA receptor acts as a _______ detector because it requires both ligand binding and depolarization.
Coincidence Detector
Which protein kinase is predominantly activated by the second messenger cAMP?
Protein Kinase A (PKA)
How does the "short form" Homer1a differ from "long form" CC-Homer in its effect on mGluR signaling?
Homer1a is an immediate early gene that uncouples mGluR signaling (dampens responsiveness), while long form Homer1c stabilizes synaptic changes.
Which enzyme is the primary target for treating Parkinson's Disease by increasing dopamine availability?
Monoamine Oxidase (MAOs)