Molecular Signaling within Neurons Flashcards
Signal amplification across several steps in a cascade is _____.
exponential
Extracellular signaling molecules:
- Small soluble organic molecules e.g. Neurotransmitters, amino acids, sugars, nucleotides
- Inorganic ions (e.g. Zn2+)
- Diffusable gases (e.g. CO & NO)
- Peptides
- Lipophilic organic molecules (e.g. endocannabinoids)
- Cell-surface expressed proteins
Cholesterol derived hormones are ____ molecules.
cell permeant
Cell-cell adhesion molecules require _____.
direct contact
metabotropic receptors are proteins consisting of ___.
7 transmembrane domains
Domains _____ make up the neurotansmitter binding region of metabotropic receptors.
II, III, VI, and VII
G-proteins bind to both the loop between domains _ and _ and the _____.
V
VI
C-terminus
Ras are small ____.
GTPases
bind and accelerate hydrolyzation of guanosine triphosphate
Heterotrimeric G-proteins are “_____.”
large
There are several classes of Gα subunits:
G(s)α (stimulatory)
G(i)α (inhibitory)
G(q)α (activates phospholipase C)
Proteins called GTPase-activating proteins (GAPs) accelerate the _____.
hydrolisis of GTP to GDP
Monomeric G-proteins are known as “_____.”
small G-proteins
“Small” G proteins belong to the _____ of small GTPases.
Ras superfamily
Monomeric proteins are homologous to the _____ found in heterotrimers.
alpha (α) subunit
A small GTPase can function independently as a _____ to bind to and hydrolyze _____.
hydrolase enzyme
GTP to form GDP
Two principal signal transduction pathways of G protein-coupled receptors:
1) Adenylyl cyclase – cAMP signal pathway (via G(α-s) and G(α-i))
2) Phospholipase C signal pathway (via G(α-q))
Activation of adenylate cyclase (via G(s-α) or G(i-α) leads to:
- cAMP formation
* protein kinase A (PKA)
The adenylyl cyclase (cAMP signal) pathway through B-adrenergic GPCR _____.
increases protein phosphorylation
The adenylyl cyclase (cAMP signal) pathway through DA(2) GPCR _____.
decreases protein phosphorylation
The Phospholipase C signal pathway through mGluR _____.
increases protein phosphorylation
activates calcium-binding proteins
Upon binding of the alpha subunit of the G-protein, _____ catalyzes the conversion of ATP to _____.
adenylate cyclase
3’,5’-cyclic AMP (cAMP)
G(α-s) and G(α-i) oppose each other through their modulation of _____.
adenylyl cyclase activity
Binding of G(α-s) (via D1 receptors) to AC _____ the synthesis of cAMP.
increases
Binding of G(α-i) (via D2 receptors) to AC _____ the synthesis of cAMP
decreases
