Ion Channels Flashcards
metabotropic receptors
Receptors that activate second messenger pathways which can affect physically separate ion channels
Each pentameric ligand gated channel subunit has four transmembrane alpha helices (M1 through M4), with ____ assembling around the central pathway.
M2
The ion is stabilized within the pore by energetic interactions with the _____.
amino acids forming the pore
ionotropic receptors
receptors that are directly coupled to ion channels
Ions must be substantially dehydrated before they pass through the _____.
channel pore
The pentameric ligand gated channels are either selective for ____, or allow permeation of both sodium and potassium.
chloride
Voltage sensing is accomplished by the ____.
S4 helices
The reversal of inactivation is called ________.
“removal of inactivation.”
Voltage gated channels of the______ have four membrane-spanning domains, each of which contains six alpha helices (S1 through S6).
KV, NaV and CaV families
Neurotransmitter receptors are either _____ or ______.
directly coupled to ion channels; activate second messenger pathways
For both K(V) and Na(V), gating is controlled by ____.
membrane potential (Vm)
______ are structural tetramers.
Aquaporin water channels
After the _____ opens, the inactivation gate closes.
activation gate
Voltage gated channels of the KV, NaV and CaV families have _____, each of which contains six alpha helices (S1 through S6).
four membrane-spanning domains
Pentameric ligand gated channels include ____, ____, _____, and _____.
GABAARs, GlyRs, nAChRs, 5-HT3Rs
What do channels select for?
1) size 2) charge 3) dehydration 4) multiple binding sites
activation
opening the gate to allow K+ to flow out of the cell
After the activation gate opens, the inactivation gate closes, a process called ______.
inactivation
Aquaporin water channels are structural ______.
tetramers
When the _____ is made positive, the gate rotates to its _____ and K+ ions flow out of the cell.
inside; open position
deactivation
closing of the gate to decay the current
_______ is accomplished by the S4 helices.
Voltage sensing
When the____ is made negative the gate rotates back to the closed position and _____.
inside of the cell; the current decays away
Receptors that activate second messenger pathways which can affect physically separate ion channels are called ________.
metabotropic receptors
When the inside of the cell is made _____ the gate rotates back to the _____ position and the current decays away.
negative; closed
After the activation gate opens, the ______ closes.
inactivation gate
The pentameric ligand gated channels are either selective for the permeation of chloride, or allow permeation of both _____ and _____.
sodium and potassium
The pentameric ligand gated channels are structurally ______.
heteropentamers
_______ have two of its four subunits bind glutamate and the other two bind glycine.
NMDA receptors
Ions are ______ in solution by waters of hydration.
energetically stabilized
Chloride channels of the CLC family are structural ____.
dimers
The S4 helices contain positively-charged Lys or Arg residues at every third position and translocate in response to _____.
changes in voltage across the membrane
Charge is an important determinant of ______.
what substances will pass through a channel
When the inside of the cell has a ____ potential with respect to the outside, the gate is held in its ____ and the current is zero.
negative; closed position
Ions must be _____ before they pass through the channel pore.
substantially dehydrated
The ion is stabilized within the pore by _____ with the amino acids forming the pore.
energetic interactions
When the inside is made _____, the gate rotates to its open position and _____ flow out of the cell.
positive; K+ ions
For both ___ and ___, gating is controlled by membrane potential (Vm).
K(V); Na(V)
The ______ are important for stabilizing the resting membrane potential.
CLC chloride channels
Ions are energetically stabilized in solution by _____.
waters of hydration
_____ of the CLC family are dimers.
Chloride channels
How does lidocaine work?
blocks the sodium/potassium channel from the intracellular side
NMDA receptors have_____ bind glutamate and the other two bind glycine.
two of its four subunits
______ of the KV, NaV and CaV families have four membrane-spanning domains, each of which contains _____.
Voltage gated channels; six alpha helices (S1 through S6).
The S4 helices contain _____ residues at every third position and translocate in response to changes in voltage across the membrane.
positively-charged Lys or Arg
____ is an important determinant of what substances will pass through a channel.
Charge
Each pentameric ligand gated channel subunit has ______, with M2 assembling around the central pathway.
four transmembrane alpha helices (M1 through M4)
NMDA receptors have two of its four subunits bind _____ and the other two bind _____.
glutamate; glycine
Receptors that are directly coupled to ion channels are called _________.
ionotropic receptors
_____ are either directly coupled to ion channels or activate second messenger pathways.
Neurotransmitter receptors
Which are the positive/basic amino acid residues?
lysine and arginine
When the _____ has a negative potential, the gate is held in its closed position and the current is ____.
inside of the cell; zero
Which are the negative/acidic amino acid residues?
glutamate or aspartate
The CLC chloride channels are important for ______.
stabilizing the resting membrane potential
