Signal Transduction Flashcards
_____ bind with receptors that also act as ion channels or they interact with G-proteins to stimulate effector enzymes to produce “second messengers”
NTs
Most ____ receptors interact with G-proteins to alter “second messenger” levels
hormone
____ hormone receptors are cytosolic receptors which travel to the nucleus to alter mRNA synthesis
steroid
Most ___ ____ receptors have intrinsic tyrosine kinase activity and cause phosphorylation of tyrosine residues on specific proteins
growth factor
In regards to being excitatory and inhibitory, give the difference between catecholamines and indolamines.
catecholamines: excitatory
indolamines: inhibitory
Epi is a catecholamine. Give its associated peptide, AA, and other characteristic
peptide: nueropeptide y
AA: glutamate
other: ATP
NE is a catecholamine. Give its associated peptide, AA, and other characteristic
peptide: enkephalins
AA: aspartate
other: zinc
Dopamine is a catecholamine. Give its associated peptide and other characteristic
peptide: somatostatin
other: arachidonic acid
Serotonin and Histamine are both indolamines. Give their associated AAs
serotonin: gamma-Aminobutyric acid
histamine: glycine
In regards to G-protein cycling, occupation of the receptor protein causes it to associate with what?
the G-protein
In regards to G-protein cycling, the receptor/G-protein complex allows a ___ to displace a ____ from the alpha-subunit
GTP; GDP
In regards to G-protein cycling, binding of GTP causes dissociation into what?
free alpha-subunit and free beta/gamma subunit
In regards to G-protein cycling, the alpha-subunit interacts with an effector protein to produce ___ ____ or occasionally open ____ channels
second messengers; ion
In regards to G-protein cycling, the alpha-subunit has intrinsic ____ activity, so the attached GTP is turned into GDP. This inactivates the alpha-subunit and causes it to rebind the beta/gamma subunit
GTPase
cAMP is made by membrane spanning enzymes called ____ ____
adenylate cyclase
note: an ATP-Mg2+ complex is the substrate and free Mg2+ is a necessary cofactor
The cAMP that is formed activates what?
protein kinase A
______ break down cAMP and terminate its activity
phosphodiesterases
Phospholipase C is a membrane bound enzyme that converts ____ into ____ and ____
PIP2; IP3; DAG
Phospholipase C is activated when a receptor-ligand complex activates a G-protein of the ___ gamily
Gq
The IP3 formed at the plasma membrane binds to receptors on the _____ _____ and causes release of intracellular ___ stores
Endoplasmic Retiuclum; Ca2+
DAG remains membrane associated. Protein kinase __ translocates from the cytosol to the membrane to become activated by DAG
C
note: activated PKC phosphorylates proteins and alters their functions
Membrane bound ____ cycles appears to be directly coupled to receptors and forms of cGMP from GTP when receptors become occupied
guanylate
____ is formed when the AA arginine is broken down
NO
note: enzyme is Nitric Oxide synthetase
NO synthetase is activated by what?
Ca/calodulin complex
NO exerts its effect by activating a soluble, cytosolic type of guanylate cyclase, thus increasing ____
cGMP
NO is a unique second messenger. Why?
it is membrane soluble - allows it to diffuse to nearby cells and increase cGMP levels in those cells as well. Such a phenomena occurs between vascular endothelial cells and nearby smooth muscle cells
cGMP exerts its effect in a variety of ways. Describe.
direct binding to ion channels; activating cGMP-dependent protein kinase
____ break down cGMP and terminate its action
phosphodiesterase
____ is a NT in both the CNS and PNS. It binds to Nicotinic and muscarinic receptors
acetylcholine
____ receptors are composed of various combinations of 5 subunits. The subunits are arranged to form a central cavity that extends across the membrane
nicotinic
The core of the nicotinic receptor protein is normally too small for ion passage. When Ach binds the receptor, what happens?
alpha-subunit (which recognizes receptor) causes conformation change which allow cations to cross the membrane through the central core
Nicotinic receptors on skeletal muscle have different alpha and beta subunits than nicotinic receptors on autonomic ganglia. True or false?
true
Ligand gated channels for other NTs like GABA, glycine, 5-HT and glutamate have structural and sequence similarity to ____ receptors
nicotinic
_____ receptors are not channels despite being activated by Ach. These receptors operate through G-proteins to alter the activity of a number of second messenger systems
muscarinic
In regards to muscarinic receptors, m1, m3, and m5 appear to activate what?
PLC through Gq
In regards to muscarinic receptors, m2 and m4 inhibit what?
couple through Gi to inhibit adenylate cyclase
All _____ receptors are coupled through G-proteins
adrenergic
In regards to adrenergic receptors, occupation of Beta-receptors stimulates what?
adenylate cyclase to produce cAMP and activate PKA
In regards to adrenergic receptors, occupation of alpha1-receptors increases and activates what?
increases IP3 and DAG and activates Ca2+ channels
note: involves PLC activation
In regards to adrenergic receptors, occupation of alpha2-receptors leads to inhibition of what?
adenylate cyclase
note: effects are probably Gi-mediated
