Download - Voltage-Gated K + Channels
Voltage-Gated K+ Channels
MK MathewNCBS, TIFRUAS – GKVK CampusBangalore IBRO Course in Neuroscience
Center for Cognitive Neuroscience & Semantics, University of LatviaRiga, LatviaAugust 21-August 29, 2013
PROPERTIES OF VOLTAGE-GATED ION CHANNELS
Voltage sensitive•Requires voltage-sensing apparatus•Requires transduction machinery
High Throughput: 108 ions/second•Protein supports an aqueous column traversing the membrane
Discriminates between Na+ and K+
•Requires a selectivity filter
1982 Noda … Numa Nature AChR a-subunit cloned from peptide information1983 Noda … Numa Nature All AChR subunits cloned1984 Noda … Numa Nature Na channel a-subunit cloned1987 Stuhmer .. Numa Eur J Biophys Xenopus expression Na channel1989 Stuhmer Conti .. Numa Nature S4 mutations in Na channel
1982 Noda … Numa Nature AChR a-subunit cloned from peptide information1983 Noda … Numa Nature All AChR subunits cloned1984 Noda … Numa Nature Na channel a-subunit cloned1987 Stuhmer .. Numa Eur J Biophys Xenopus expression Na channel1989 Stuhmer Conti .. Numa Nature S4 mutations in Na channel
1987 Kamb Iverson Tanouye Cell
1987 Papazian … Jan Science Shaker Cloning
!988 Pongs … Ferrus EMBO J
N H 2 C O O H
++++
T1
++++
N H 2
C O O HT12 0 m s-20 m V
+2 0 m V
+ 6 0 m V
5 0 0 n A
5 0 m s
hKv1.1
hKv1.40.0
0.2
0.4
0.6
0.8
1.0
1.2
P oten tia l (m V )
h K v 1 .1
h K v1 .2h K v 1 .4
Po
ELECTROPHYSIOLOGICAL PROPERTIES OF HUMAN K+ CHANNELS
I II III IV selctivity
Ca E E E E Ca/Na~ 3000
Na D E K A Na/Ca ~ 1000
Ca start E E K E Na/Ca ~ 100
RajGanesh et al (2000) Proteins
hKv1.1 FRIFKLSRHSKGLQILGQTLKASMRELGLLIFFLFIhKv1.2 FRIFKLSRHSKGLQILGQTLKASMRELGLLIFFLFIhKv1.4 FRIFKLSRHSKGLQILGHTLRASMRELGLLIFFLFIhKv1.5 FRIFKLSRHSKGLQILGKTLQASMRELGLLIFFLFIShaker FRIFKLSRHSKGLQILGRTLKASMRELGLLIFFLFIhKv2.1 LRILKLARHSTGLQSLGFTLRRSYNELGLLILFLAMKvAP LRILLIISRGSKFLSAIADAADKIRFYHLFGAVMLT :**: : :.. : . . *: .:
Sequence Alignment of The S4-S5 Region
S4 S5
Ken (1991) PNAS
hKv1.1 FRIFKLSRHSKGLQILGQTLKASMRELGLLIFFLFIhKv1.2 FRIFKLSRHSKGLQILGQTLKASMRELGLLIFFLFIhKv1.4 FRIFKLSRHSKGLQILGHTLRASMRELGLLIFFLFIhKv1.5 FRIFKLSRHSKGLQILGKTLQASMRELGLLIFFLFIShaker FRIFKLSRHSKGLQILGRTLKASMRELGLLIFFLFIhKv2.1 LRILKLARHSTGLQSLGFTLRRSYNELGLLILFLAMKvAP LRILLIISRGSKFLSAIADAADKIRFYHLFGAVMLT :**: : :.. : . . *: .:
Phenylalanine mutations in hKv 1.4Val/Ala mutations in Shaker
McCormack et al., (1991)Judge et al., (2002)
Mutant V1/2 (mV)
Wt 1±5V1 100±6V2 69±7V3 -5±2V4 -22±3V5 -7±7V2A3 32±5
McCormack et al (91) PNAS
V1/2
L1 L2 L3 L4 L5
D.V. Ivanov et al./FEBS Letters 539 (2003) 156-160
KCNRG : K (Potassium) / CN (Channel) / RG (Regulator)
++++
T1
S1 S2 S3 S4 S5 p S6
Ball
T1KCNRG (monomer)n ?
0
0.5
1
1.5
hKv 1.4 hKv 1.4+KCNRGNo
rma
lize
d F
lou
res
ce
nc
e
* p < 0.05
*5um
Surface Expression Analysis
KCNRG reduces Surface targeting of hKv 1.4
Hyder (2010)