voltage-gated k + channels
DESCRIPTION
Voltage-Gated K + Channels. MK Mathew NCBS, TIFR UAS – GKVK Campus Bangalore. IBRO Course in Neuroscience Center for Cognitive N euroscience & Semantics, University of L atvia Riga, L atvia August 21-August 29, 2013. PROPERTIES OF VOLTAGE-GATED ION CHANNELS. Voltage sensitive - PowerPoint PPT PresentationTRANSCRIPT
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
Sodium 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
Xenopus oocytes
Two Electrode Voltage clamp
N H 2 C O O H
++++
T1
++++
N H 2
C O O HT12 0 m s-20 m V
+20 m V
+ 60 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
-40 mV
0 mV
+40 mV
50ms1A
hKv1.4
+ 40 mV500 nA
50 ms
- 40 mV
0 mV
Doyle et al., Science 1998; 280: 69
KcsA
Doyle et al., Science 1998; 280: 69 Jiang et al., Nature 2002 417; 523
Gary Yellen
Doyle et al., Science 1998; 280: 69
KcsA
Zhou .. MacKinnon (01) Nature
Varma & Rempe (2007) Biophys J 93:1093–1099
Zhou .. MacKinnon (01) Nature
Payandeh .. Catterall (2011) Nature
I II III IV selctivityCa E E E E Ca/Na~
3000Na D E K A Na/Ca ~
1000Ca start E E K E Na/Ca ~
100
RajGanesh et al (2000) Proteins
Doyle et al., Science 1998; 280: 69
KcsA
Kv 1.2 Crystal Structure
MacKinnon ,2005
… Catterall (2006) PNAS
Pathak .. Isacoff (2007) Neuron
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 1.4 Val/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
Bezanilla (2000) Physiol Rev 80, 555 - 592
Schoppa Sigworth (98) JGP
Gating chargeSensor Movement
Po
Kv 1.2 Crystal Structure
MacKinnon ,2005
L312M-L326V DV1/2 = 0 mVV406L–L312M DV1/2 = -42 mVA305L-L312M DV1/2 = +18 mV
Sanjeev
Sanjeev, Nagarajan J Physiol
OPEN STATE
Sanjeev, Nagarajan
CLOSED STATE
CLOSED OPEN
Sanjeev, Nagarajan J Physiol
Ledwell Aldrich (99) JGP
Gating charge
Po
Ledwell Aldrich (99) JGP
Gating charge
Po
ACTIVATED STATE
CLOSED ACTIVATED OPEN
Sanjeev, Nagarajan J Physiol
Kaczmarek Nature Reviews Neuroscience 7, 761–771 (October 2006) | doi:10.1038/nrn1988
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+KCNRGNor
mal
ized
Flo
ures
cenc
e
* p < 0.05
*5um
Surface Expression Analysis
KCNRG reduces Surface targeting of hKv 1.4
Hyder (2010)
KS Krishnan 1976
Ken McCormack
YD RamuBaron ChandaAnurag VarshneyKavitha SSanjeev UpadhyayS NagarajanHyder Usman
5um