Ion Channels & Transporters Flashcards

1
Q

Ion channels

A

use concentration and electrical gradients; allow diffusion
usually selective for specific ions; permeability
most gated by signals (chemical/electrical)

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2
Q

Voltage gated ion channels

A

Na+ ; out->in
Ca2+; out->in
K+; in->out
Cl-; out->in

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3
Q

ligand gated channels

A

neurotransmitter receptor
ca2+ activated K+ channel
cyclic nucleotide gated channel (cAMP, cGMP, GCPR); K+ outward, Na+ inward
VR-1 receptor; capsaicin

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4
Q

measuring ion channel activity

A

cell-attached recording
whole cell recording
inside out recording
outside-out recording

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5
Q

measuring single Na+ channel

A

short, quick response; inward; early

closed->(depolarization) open->inactivating->inactivated (hyperpolarized)->closed

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6
Q

measuring single K+ channel

A

delay, long lasting response; outward; later

closed->(depolarization) closed->open->open (hyperpolarized)->closed

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7
Q

transporters

A

ions/small molecules against their gradients/electrochemical concentration/ electrical potential
require energy; ATP
creation of ion concentration gradient

ATPase pumps - NA+/K+ pump, Ca2+ pump(use H+)
Ion exchangers - Na+/Ca2+ exchanger, Na+/K+/Cl- cotransporter, K+/Cl- cotransporter, Na+/H+ exchanger, Na+/neurotransmitter transporter (Na+ and GABA,Dopamine)

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8
Q

Na+/K+ ATPase

A
[Na+] greater out than in
[K+] greater in than out
3Na+out 2K+in
Electrogenic; cell negative inside
Na+ bind -> ATP hydrolysis&phosphorylation -> K+ bind -> dephosphorylation
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9
Q

Ouabain

A

inhibit Na+/K+ ATPase

post stimulus hyperpolarization blocked

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10
Q

Ca2+ pump

A
ATP binds with Mg2+, 2 Ca2+ in place
phosphorylation
2 Ca2+ and ADP detached. 2H+ in place
Mg2+ and P detached 
2Ca2+ comes in,
2H+ detached
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11
Q

Transporters

A

do not use ATP

Uniporter; glucose, amino acids
(cotransporter) symporter & antiporter - one against gradient, one down gradient

neurotransmitter&precursor taken into nerve/vesicle via a transporter

  • EAAT; excitatory amino acid transport; glutamate from cleft to nerve
  • VGLUT; vesicle glutamate transport; glutamate from terminal into vesicle
  • VIATT; vesicle inhibitory amino acid transporter; GABA into vesicle
  • Glycine transporter; ?
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12
Q

topology of voltage gated Na+ channel and K+ channels

A

Na+ channel; 4 domain monomer
K+ channel; tetramer

  • Ca2+ channel; similar to Na+ channel
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13
Q

K+channel

A

tetrameric protein
6 sub domains
1 pore-segment

sub domain 4 contains (+) residues; voltage sensor
N-terminal (4) is inactivating segment

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14
Q

Na+ channel

A
monomeric
4 homologous domains
structurally like K+ channel subunits
one inactivating domain between III&IV domains
analogous S4 domain are voltage sensors
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