PMID- 12905030
OWN - NLM
STAT- MEDLINE
DCOM- 20040914
LR  - 20181113
IS  - 0031-6768 (Print)
IS  - 0031-6768 (Linking)
VI  - 447
IP  - 1
DP  - 2003 Oct
TI  - A radiolabeled peptide ligand of the hERG channel, [125I]-BeKm-1.
PG  - 55-63
AB  - The wild-type scorpion toxin BeKm-1, which selectively blocks human ether-a-go-go 
      related (hERG) channels, was radiolabeled with iodine at tyrosine 11. Both the 
      mono- and di-iodinated derivatives were found to be biologically active. In 
      electrophysiological patch-clamp recordings mono-[127I]-BeKm-1 had a 
      concentration of half-maximal inhibition (IC50 value) of 27 nM, while wild-type 
      BeKm-1 inhibited hERG channels with an IC50 value of 7 nM. Mono-[125I]-BeKm-1 was 
      found to bind in a concentration-dependent manner and with picomolar affinity to 
      hERG channel protein in purified membrane vesicles from transfected human 
      embryonic kidney cells (HEK-293). Under optimized conditions the equilibrium 
      dissociation constant ( Kd) values from saturation and kinetic binding analysis 
      were 13 and 14 pM, respectively. Both the association and dissociation of 
      [(125)I]-BeKm-1 were fast (association rate constant, k(on)=3.6 x 10(7) 
      M(-1)s(-1); dissociation rate constant, k(off)=0.005 s(-1)). Wild-type BeKm-1 
      displaced binding of [125I]-BeKm-1 with half-maximal inhibitory concentrations of 
      44 pM. In contrast, competition experiments with a BeKm-1 mutant BeKm-1-K18A, in 
      which the toxin interaction site is disrupted, resulted in a drop in affinity by 
      more than 300-fold as compared to the wild-type toxin. Iberiotoxin and apamin, 
      peptide inhibitors of Ca2+-activated K+-channels, had no effect on [125I]-BeKm-1 
      binding. Adding the classical rapid delayed rectifier current (IKr) blocker 
      E-4031 reduced binding of [125I]-BeKm-1 to the hERG channel to an IC50 of 7 nM. 
      In autoradiographic studies on rat hearts, binding of [125I]-BeKm-1 was 
      dose-dependent and could partially be displaced by the addition of excess amounts 
      of non-radioactive BeKm-1. The density of the radioactive signal was equally 
      distributed in the myocardium of both the ventricle and atria indicating a 
      homogenous expression of hERG channels throughout the heart.
FAU - Angelo, Kamilla
AU  - Angelo K
AD  - The Wolfson Institute for Biomedical Research, Cruciform Building, University 
      College London, Gower Street, London, WC1E 6BT, UK. k.angelo@ucl.ac.uk
FAU - Korolkova, Yuliya V
AU  - Korolkova YV
FAU - Grunnet, Morten
AU  - Grunnet M
FAU - Grishin, Eugene V
AU  - Grishin EV
FAU - Pluzhnikov, Kirill A
AU  - Pluzhnikov KA
FAU - Klaerke, Dan A
AU  - Klaerke DA
FAU - Knaus, Hans-Gunther
AU  - Knaus HG
FAU - Moller, Morten
AU  - Moller M
FAU - Olesen, Soren-Peter
AU  - Olesen SP
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20030805
PL  - Germany
TA  - Pflugers Arch
JT  - Pflugers Archiv : European journal of physiology
JID - 0154720
RN  - 0 (BeKm-1 toxin)
RN  - 0 (ERG1 Potassium Channel)
RN  - 0 (Ether-A-Go-Go Potassium Channels)
RN  - 0 (Iodine Radioisotopes)
RN  - 0 (KCNH2 protein, human)
RN  - 0 (Ligands)
RN  - 0 (Peptides)
RN  - 0 (Potassium Channel Blockers)
RN  - 0 (Potassium Channels)
RN  - 0 (Potassium Channels, Voltage-Gated)
RN  - 0 (Scorpion Venoms)
SB  - IM
MH  - Animals
MH  - Cell Line
MH  - Dose-Response Relationship, Drug
MH  - ERG1 Potassium Channel
MH  - Ether-A-Go-Go Potassium Channels
MH  - Humans
MH  - Iodine Radioisotopes/metabolism
MH  - Ligands
MH  - Male
MH  - Peptides/*metabolism
MH  - Potassium Channel Blockers/*metabolism
MH  - Potassium Channels/*metabolism
MH  - *Potassium Channels, Voltage-Gated
MH  - Protein Binding/physiology
MH  - Rats
MH  - Scorpion Venoms/*metabolism
EDAT- 2003/08/09 05:00
MHDA- 2004/09/15 05:00
CRDT- 2003/08/09 05:00
PHST- 2003/02/10 00:00 [received]
PHST- 2003/05/20 00:00 [accepted]
PHST- 2003/08/09 05:00 [pubmed]
PHST- 2004/09/15 05:00 [medline]
PHST- 2003/08/09 05:00 [entrez]
AID - 10.1007/s00424-003-1125-9 [doi]
PST - ppublish
SO  - Pflugers Arch. 2003 Oct;447(1):55-63. doi: 10.1007/s00424-003-1125-9. Epub 2003 
      Aug 5.