Enzyme Coupled Receptors Flashcards
What are the types of enzyme coupled receptors?
Receptor Tyrosine Kinase and Tyrosine-Kinase associated receptors
Describe Receptor Tyrosine kinases -
stimulated by growth factor or membrane bound ligands, intracellular domain associated with adaptor proteins, receptors dimerize
How does activation of insulin signaling occur?
Insulin binds to receptor causing cross phosphorylation.
Binding to IRS-1 occurs and it is phosphorylated, binding to phosphoinositide 3 kinase
P3K converts PIP2 to PIP3, activating PDK1.
How does glucose uptake occur in the insulin signaling pathway?
Protein Kinase B bound to PIP3 is phosphorylated by PDK1.
Activated PKB phosphorylates GSK3 and inactivates it.
Inactive GSK3 can’t convert glycogen synthase to its inactive form, so glycogen synthase remains active, and glucose is synthesized.
Describe short lived activation Ras through flourescence resonance energy transfer.
GDP bound (inactive) RAS will emit light at 528 nm when exposed to light at 476. GTP bound RAS (active) will emit light at 617 nm when exposed to light at 476 nm.
How does RAS activate MAPK signaling
GTP bound RAS activates MAP kinase kinase kinase, which phosphorylates MAP kinase kinase, which phosphorylates MAPK, which phosphorylates proteins and transcription regulators, causing changes in protein activity and changes in gene expression.
Describe the first part of the PI-3K-Akt signaling pathway for cell survival.
PI 3 kinase binds to activated RTK, causing PIP3 to phosphorylate, attracting PDK1 and AKT.
Describe the second part of the PI-3K-Akt signaling pathway for cell survival.
Phosphorylated and Active Akt phosphorylates Bad to inhibit it and allows apoptosis inhibitory protein to be activated, resulting in cell survival.
This pathway is very useful for TOR, an anticancer drug.
Describe cytokine receptors and the kind of receptor they are.
They are tyrosine kinase associated receptors that associate with cytoplasmic kinases called Janus Kinases.
JAKs activate signal transducers and activators of transcription. They are required for cell proliferation, death, migration and many other functions.
How do you determine protein order in a pathway?
If overactive Ras being introduced causes signaling to be restored, Ras acts downstream of that protein. If introducing overactive Ras does not restore signaling, the protein acts downstream of ras.
How does RTK signaling occur via Ras?
Adaptor protein binds to activated RTK, recruiting Ras GEF, causing a Ras protein to activated by exchanging its GDP for a GTP. Activated Ras can now stimulate several downstream signaling pathways.
Describe notch signaling
unspecified epithelial cells surround nerve cells that express signaling molecule, which bind to epithelial Notch receptors, inhibiting them.
How does notch signaling work?
Contact dependent activation occurs, in which Delta binds to Notch, causing cleaved Notch tail to migrate to nucleus and cause transcription of Notch responsive genes.
Describe Wnt/B-catenin signaling when Wnt signal is present.
Receptors Frizzled and LRP are activated by Wnt, recruiting dishevelled and freeing B-catenin.
Stable B-catenin functions as transcriptional coregulator to transcribe Wnt target genes.
What happens when Wnt signal isn’ present?
B-catenin is phosphorylated, polyubiquitylated, and degraded in proteasomes.
