CHARYBDOTOXIN, DENDROTOXIN AND MAST-CELL DEGRANULATING PEPTIDE BLOCK THE VOLTAGE-ACTIVATED K+-CURRENT OF FIBROBLAST CELLS STABLY TRANSFECTED WITH NGK1 (KV1.2) K+-CHANNEL COMPLEMENTARY-DNA

被引:42
作者
WERKMAN, TR
KAWAMURA, T
YOKOYAMA, S
HIGASHIDA, H
ROGAWSKI, MA
机构
[1] NINCDS, EPILEPSY RES BRANCH,NEURONAL EXCITAB SECT,BLDG 10, ROOM 5N-205, BETHESDA, MD 20892 USA
[2] KANAZAWA UNIV, SCH MED, NEUROINFORMAT RES INST, KANAZAWA, ISHIKAWA 920, JAPAN
关键词
D O I
10.1016/0306-4522(92)90216-O
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
The blocking actions of the K+ channel toxins charybdotoxin, dendrotoxin and mast cell degranulating peptide were studied in B82 mouse fibroblast cells transformed to express NGK1 (Kv1.2) K+ channels. All three toxins were potent blockers of the K+ current in these cells, with K(D) values of 1.7, 2.8 and 185 nM, respectively. The toxin block exhibited a weak voltage-dependence with the degree of inhibition decreasing at positive membrane potentials. For charybdotoxin and dendrotoxin, reducing [K+]i did not increase the fractional block, demonstrating that the relief of block at positive membrane potentials is not due to displacement of the toxin molecules by outward flow of K+ ions. A voltage-jump protocol was used to determine the rates of binding and unbinding of dendrotoxin and mast cell degranulating peptide; binding of charybdotoxin was too rapid to be quantitatively evaluated in this manner. The binding rates (dendrotoxin, approximately 5 x 10(7)/M per s; mast cell degranulating peptide, approximately 0.8 x 10(7)/M per s) were largely voltage-independent, suggesting that association of the toxin molecules with the channel is diffusion limited. The rates of unbinding (dendrotoxin, approximately 0.3/s; mast cell degranulating peptide, approximately, 3/s at +60 mV) of both toxins increased e-fold per approximately 40 mV change in membrane potential, thus accounting for the voltage-dependence of the equilibrium block. Internal perfusion with the three toxins failed to affect the K+ current (in contrast to internal tetraethylammonium which strongly blocked the current), indicating that the toxins exert their blocking action by binding to extracellular sites.
引用
收藏
页码:935 / 946
页数:12
相关论文
共 55 条
[1]   CHARYBDOTOXIN BLOCK OF SINGLE CA-2+-ACTIVATED K+ CHANNELS - EFFECTS OF CHANNEL GATING, VOLTAGE, AND IONIC-STRENGTH [J].
ANDERSON, CS ;
MACKINNON, R ;
SMITH, C ;
MILLER, C .
JOURNAL OF GENERAL PHYSIOLOGY, 1988, 91 (03) :317-333
[2]  
BRAU ME, 1990, J PHYSIOL-LONDON, V420, P365, DOI 10.1113/jphysiol.1990.sp017918
[3]   TOXINS IN THE CHARACTERIZATION OF POTASSIUM CHANNELS [J].
CASTLE, NA ;
HAYLETT, DG ;
JENKINSON, DH .
TRENDS IN NEUROSCIENCES, 1989, 12 (02) :59-65
[4]   SIMPLIFIED GENE NOMENCLATURE [J].
CHANDY, KG ;
DOUGLAS, J ;
GUTMAN, GA ;
JAN, L ;
JOHO, R ;
KACZMAREK, L ;
MCKINNON, D ;
NORTH, RA ;
NUMA, S ;
PHILIPSON, L ;
RIBERA, AB ;
RUDY, B ;
SALKOFF, L ;
SWANSON, R ;
STEINER, D ;
TANOUYE, M ;
TEMPEL, BL .
NATURE, 1991, 352 (6330) :26-26
[5]  
Cook NS., 1990, POTASSIUM CHANNELS S
[6]   2 TYPES OF FAST K+ CHANNELS IN RAT MYELINATED NERVE-FIBERS AND THEIR SENSITIVITY TO DENDROTOXIN [J].
CORRETTE, BJ ;
REPP, H ;
DREYER, F ;
SCHWARZ, JR .
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY, 1991, 418 (04) :408-416
[7]  
DONEVAN SD, 1992, MOL PHARMACOL, V41, P727
[8]  
DREYER F, 1990, REV PHYSIOL BIOCH P, V115, P93
[9]   SELECTIVE COUPLING WITH K+ CURRENTS OF MUSCARINIC ACETYLCHOLINE-RECEPTOR SUBTYPES IN NG108-15 CELLS [J].
FUKUDA, K ;
HIGASHIDA, H ;
KUBO, T ;
MAEDA, A ;
AKIBA, I ;
BUJO, H ;
MISHINA, M ;
NUMA, S .
NATURE, 1988, 335 (6188) :355-358
[10]   PURIFICATION, SEQUENCE, AND MODEL STRUCTURE OF CHARYBDOTOXIN, A POTENT SELECTIVE INHIBITOR OF CALCIUM-ACTIVATED POTASSIUM CHANNELS [J].
GIMENEZGALLEGO, G ;
NAVIA, MA ;
REUBEN, JP ;
KATZ, GM ;
KACZOROWSKI, GJ ;
GARCIA, ML .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1988, 85 (10) :3329-3333