Signal Transduction Flashcards
How do steriods travel in the bloodstream?
Bind to Albumin
List pathway of steroids to gene expression
1) steriod binds to receptor in cytoplasm 2) Receptor/Ligand complex =>nucleus 3) Binds to DNA =>gene transcription
Autocrine
Same or Identical cell responds to signal
Paracrine
single cell secrets ligands that bind only to phenotypically different cells within short distance
Endorcrine signaling
Utilizes bloodstream to transport hormones over LONG distances
Neuronal signaling
Nerve cell signals to non-neuronal target cell
Nitric oxide has what effect on smooth muscle cells
relaxation = dilation of blood vessels
Arginine becomes Nitric Oxide after what ligand binds to endothelial cell?
Acetylcholine
What is nitroglycerine
Drug that produces Nitric Oxide and causes blood vesells to dilate; relieves angina
Kinase proteins can transfer terminal phospate from ATP to OH group of which three amino acids?
Serine Threonine Tyrosine
G-Protein coupled receptors are composed of what three subunits?
1) GTPase 2) Beta (B) 3) Gamma (y)
How do G-Protein receptors deactivate?
GTPase’s own enzymatic activity turns GTP -> GDP
What is the action of Ga-s/GTP
activates enzyme adenylate cyclase
What is the action of Ga-i/GTP
inhibits enzyme adenylate cyclase
What is the action of Ga-q/GTP
activates enzymes phospholipase C
Adenylate cyclase activates what?
Cyclic AMP (cAMP)
What is the role of cAMP?
cAMP binds to regulatory subunit of Protein Kinase A which causes the subunit to disassemble -> PKA activated
what enzyme deactivates cAMP?
cAMP phosphodiesterase
Ga-s are a part of what type of receptors?
B-adrenergic receptors
Ga-i are a part of what type of receptors?
a2-adrenergic receptors
Ga-q are a part of what type of receptors?
a1-adrenergic receptors
When Ga-q binds to GTP, what does it activate?
phospholipase C (PLC)
What is the role of Phospholipase C (PLC)?
Cleaves PIP2 forming DAG and IP3
what is the role of IP3 in cells?
IP3 binds to endoplasmic reticulum and causes Ca2+ to be released
what is the role of CA2+ in a1-adrenergic signaling mechanism?
CA2+ binds to Protein Kinase C and recruits it to DAG and then PKC is fully activated
Describe structure of receptor tyrosine kinases (RTK)?
transmembrane proteins that have an extracellular portion that binds to ligand and intracellular portion that is able to phosphorylate itself
describe structure of insulin receptor
receptor tyrosine kinase; dimer composed of subunits alpha and beta
What key player does insulin receptor activate?
Insulin receptor substate 1 (IRS-1)
List process of RTK signaling
1) ligand binds to RTK 2) RTK dimerizes 3) each receptor phosphorylates each other 4) GRB2 binds to receptor 5) SOS binds to GRB2 6) RAS binds to SOS 7) Activated RAS activates MAPK
what are the effects of acivated MAPK?
1) cell division 2) altered gene expression 3) cell survival
Name a pathway that Insulin Receptor Substrate 1 activates
IRS-1 activates PI3K what activates AKT to increase glucose uptake
Does phosphorylation activate or inhibit enzymatic activity?
phosphorylation may activate OR inhibit enzymatic activity
What state does insulin favor?
dephosphorylation
What state does glucagon favor?
phosphorylation
How does glucagon cause phosphorylation
Via Ga-s receptor pathway -> activates PKA
Steriod proteins bind to thier receptors where?
In the cytoplasm
Nitric Oxide must perform its signaling function quickly because
It has a short half life
Ras is bound to what in its deactivated state?
GDP
The ligands Epinephrine and Glucagon act on what type of signaling receptor?
G-protein coupled receptor
Nitric Oxide binds to in type of cells
- Guanylyl Cyclase
- smooth muscle cells -> causes relaxation
G couple protein receptors (Ga-s; Ga-i; Ga-q) can be stimulated by what common ligand?
Epinephrine
