11.2 Signal Transduction II Flashcards
All GPCRs have _______ transmembrane domains.
7
All GPCRs activate _____________ .
G protein complexes
G-proteins are all ________trimers made up of an ______ subunit.
Membrane-associated trimers which are made up of an alpha, beta and gamma subunit.
An activated GPCR has GTP or GDP bound to it?
GTP
Some activated G-proteins disassociate into _____ and _______ subunits.
Alpha
Beta-gamma
Gs and Gi
Stimulatory and inhibitory families of G proteins
Golf
G protein found in olfactory neurons
G12/13
Family of G proteins that regulate the function of the cytoskeleton by altering the activity of Rho (actin cytoskeleton)
Protein kinase A (PKA)
Master signaling kinase involved in G protein linked receptor signaling pathway. Acts to phosphorylate downstream effector targets.
Adenylyl cyclase
Membrane associated enzyme (long brown one in picture) that catalyses the formation of cyclic AMP from ATP.
cAMP
A “second message” in the chain of signals and is referred to as a second messenger. cAMP binds to negative regulatory subunits attached to PKA and causes them to release the active PKA.
One example molecule of what PKA can activate is _______.
PKA can activate a transcription factor called CREB which then leads to changes in gene expression patterns. There are other targets for PKA not involved in gene expression
ATP is modified by _________ to form ______.
Adenylyl cyclase
cAMP
cAMP can be deactivated by _________.
cAMP phosphodiesterase. This converts cAMP to AMP (adenosine monophosphate)
The result of inhibiting the mechanism of cAMP deactivation leads to the _________ of signaling pathways regulated by G proteins.
Stimulation
Give a few examples of signaling systems that use G proteins for their function.
- Thyroid gland uses thyroid-stimulating hormone (TSH) to secrete the thyroid hormone
- Heart uses adrenaline to increase heart rate and force of contraction
Phospholipase C
Membrane associated enzyme that is activated by an activated G protein trimer. Phospholipase C cleaves phosphoinositides which are part of the membrane and results in the release of a tri-phosphorylated inositol to the cytoplasm.
Diacylglycerol
The part of the lipid left in the membrane when phosphoinositides are cleaved by a G protein
IP3
Inositol triphosphate. IP3 can bind to calcium channels on the Endoplasmic reticulum and results in the release of calcium into the cytoplasm.
(Involved in G protein signaling via Phospholipase C)
Calcium can be transported out of the cell by
- Calcium pump
2. Sodium/calcium anti port
Calcium can be sequestered into the _____ or ______ using _____ and ________.
- ER using ATP pumps
2. Mitochondria using energy from the pH gradient created by the electron transport chain
Free calcium in the cytoplasm can be bound using ________.
Calcium sequestering protein
Calmodulin
Conserved protein that has 4 calcium binding domains, 2 present on each side of the protein. When calcium binds to it, it causes the protein to fold in the middle and the folded protein can wrap itself around regulatory domains of other proteins.
(Calcium/calmodulin dependent signaling)
Mice lacking a brain specific form of CAM kinase 2 have difficulty …
Remembering things
