Postsynaptic Receptors Flashcards
CONVERSION of a message from one form (neurotransmitters) into another (increased membrane conductance. Is know as what?
Transduction
The transduction mechanism is described as direct-gating
(or ligand-gating). This is used by which type of receptors?
Ionotropic
The transduction mechanism is described as indirectgating. This is used by which type of receptors?
Metabotropic-type receptors
Ionotropic-type receptors uses ___ gating that neurotransmitter binding to the receptor
causes a CONFORMATIONAL CHANGE in the ion channel complex
to open the gate and provide conductance across the
membrane for a selected ion, or ions.
Direct
The neuromuscular ACh receptor is classified as _____.
Nicotinic cholinergic
two molecules of ACh must bind
to the two ___subunits to activate
the receptor
Alpha
The selectivity filter of ___ is cation selective,
providing conductance for both Na+ and K+
Neuromuscular junction
INDIRECT GATING is used by what type of ___ receptors?
Metabotropic-type
Is there an measurable delay in metabotropic receptors compared to ionotropic receptors?
YES.
With ___ receptors, the extracellular signal (neurotransmitter)
must be brought into the cell (“internalized”) to effect the functional
response
Metabotropic
What is the first messenger that takes extracellular message into the cell?
Neurotransmitter
- ___ (→ “first messenger”) binds to
the receptor - the ligand-activated receptor complex activates a
G-protein (_____) - the activated G-protein translocates along the
membrane to activate a _____. - the activated primary effector generates an
intracellular _____. - the second messenger activates a _____.
- neurotransmitter
- transducer
- primary effector
- second messenger
- secondary
effector
Is second intracellular?
Yes.
What is the function of the second messenger?
Process the message (internalizing) brought into intracellular side from extracellular side.
What enzyme serves as the primary effector?
Adenylyl cyclase
What will activate adenylyl cyclase?
G-protein
When G- protein is in an inactive state, adenylyl cyclase is___.
INACTIVE (G-protein will not activate adenylyl cyclase)
The signaling cascade starts with ___ binding to its
receptor, which activates the ___, leading to activation of the
___ and generation of the second messenger.
- neurotransmitter
- G-protein
- primary effector
The ligand-receptor complex
continues to reactivate inactive Gproteins until the neurotransmitter
_____ from the receptor
detaches
To cause the gate on an ion channel to open, there must be an
intracellular signal … this is provided by ___ of the
channel.
phosphorylation
Attaching an inorganic phosphate (Pi
) to an internal segment of the
membrane-spanning channel. This is known as?
Phosphorylation
When a channel is DE-phosphorylated, what happens?
Channel will close
When a channel is phosphorylated, what happens?
Channel will open
What is the second messenger known as?
cAMP
The intracellular target for cAMP (the
second messenger) is cAMP-dependent kinase which is known as_____.
protein kinase A, or PKA
phosphodiesterases ___ cAMP.
inactivate
protein phosphatases remove
_____from proteins.
phosphate groups
cAMP is activated by___.
Activated adenylyl cyclase.
Adenylyl cyclase is activated by___.
G- protein
G-protein is activated by___.
Neurotransmitter, stimulating postsynaptic receptor
When neurotransmitter detaches from postsynaptic receptors we want the ion channels to ___.
Close: signaling communication is over.
Why do we want to remove neurotransmitter from postsynaptic receptor after message is conveyed?
So it won’t keep repeating the same message over and over again.
Ionic channel wont close unless _____.
Dephosphorylated via protein phosphatases
Another G-protein coupled signaling mechanism that is
commonly employed in neurons is the _____.
Phosphoinositol system
phospholipase Cβ (PLC) is the primary
effector activated by the_____.
G-protein
subunit Gq
Both IP3 (inositol trisphosphate) and DAG (diacylglycerol) are generated as \_\_\_\_\_through cleavage of phosphatidylinositol bisphosphate (PIP2) by phospholipase C
Second messengers
DAG (diacylglycerol) will bind with the _____ of protein kinase C
Regulatory subunit
IP3 signals via a receptor along
the _____ for
that organelle to release Ca++ into
the cytosol
Endoplasmic reticulum
Secondary Effectors:
Protein kinase C is activated by ___.
DAG
Ca++/calmodulin dependent protein kinase is
activated when Ca++ binds to ___
Calmodulin
The effectiveness of signaling through the calcium-calmodulin pathway
is based upon an acute increase in the ______.
Cytosolic Ca++ concentration
The mechanism
for indirect activation of a
K+ channel via a _____receptor.
Muscarinc
acetylcholine
Nicotinic cholinergic
receptors are ___ gated
Directly
What is the first messenger, receptor, and second messenger(s) in the cAMP system?
Norepinephrine; Beta-adrenergic receptor; cAMP
What is the first messenger, receptor, and second messenger(s) in the Phosphoinositol system?
ACh; Type 1 Muscarinic ACh receptor; IP3 and DAG
What is the first messenger, receptor, and second messenger(s) in the Direct G protein-gating system?
ACh; Type 2 Muscarinic ACh receptor; G protein-gated K+ channel
In general, G-proteins function as a molecular _____
operated through binding and then release of neurotransmitter
from its postsynaptic receptor.
on – off switch
α-GDP is active/inactive?
Inactive
α-GTP is active/inactive?
Active
_____ receptors: ion channels DO NOT respond
immediately to neurotransmitter binding and releasing
from the receptor.
Metabotropic
_____ receptors: ion channels RESPOND
immediately to neurotransmitter binding and releasing
from the receptor.
Ionotropic
The state of ___ to determine whether the channel is open or closed.
Phosphorylation
Protein kinase A and phosphoprotein phosphatase-1 are _____ signals that are regulated by _____ signaling via membrane receptors.
Intracellular; external signaling
The “strength” of phosphorylation in response to cAMP is: _____ when PP-1 is inhibited.
Enhanced
The “strength” of phosphorylation in response to cAMP is: _____ (lessened) when PP-1 is active.
Diminished
PP-1 (phosphatase-1 ) is regulated via another intracellular signaling molecule, _____.
Inhibitor-1
\_\_\_\_\_ modulates (lessens) channel phosphorylation in response to cAMP by causing the DISINHIBITION of PP-1
calcineurin
Calcineurin is activated by?
Calcium
