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Sodium channel from rat brain. Reconstitution of voltage-dependent scorpion toxin binding in vesicles of defined lipid composition

Journal Article · · J. Biol. Chem.; (United States)
OSTI ID:6235557
; ;

Purified sodium channels incorporated into phosphatidylcholine (PC) vesicles mediate neurotoxin-activated SSNa influx but do not bind the alpha-scorpion toxin from Leiurus quinquestriatus (LqTx) with high affinity. Addition of phosphatidylethanolamine (PE) or phosphatidylserine to the reconstitution mixture restores high affinity LqTx binding with KD = 1.9 nM for PC/PE vesicles at -90 mV and 36 degrees C in sucrose-substituted medium. Other lipids tested were markedly less effective. The binding of LqTx in vesicles of PC/PE (65:35) is sensitive to both the membrane potential formed by sodium gradients across the reconstituted vesicle membrane and the cation concentration in the extravesicular medium. Binding of LqTx is reduced 3- to 4-fold upon depolarization to 0 mV from -50 to -60 mV in experiments in which (Na+)out/(Na+)in is varied by changing (Na+)in or (Na+)out at constant extravesicular ionic strength. It is concluded that the purified sodium channel contains the receptor site for LqTx in functional form and that restoration of high affinity, voltage-dependent binding of LqTx by the purified sodium channel requires an appropriate ratio of PC to PE and/or phosphatidylserine in the vesicle membrane.

Research Organization:
Univ. of Washington, Seattle
OSTI ID:
6235557
Journal Information:
J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 21; ISSN JBCHA
Country of Publication:
United States
Language:
English

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Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL ISOTOPES
ALKALI METALS
ANIMALS
ANTIGENS
ARACHNIDS
ARTHROPODS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BODY
BRAIN
CATIONS
CENTRAL NERVOUS SYSTEM
CHARGED PARTICLES
CONFIGURATION INTERACTION
ELECTRIC POTENTIAL
ELEMENTS
ESTERS
IN VITRO
INVERTEBRATES
IODINE ISOTOPES
IONS
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
LIPIDS
MAMMALS
MATERIALS
MEMBRANE TRANSPORT
METALS
NERVOUS SYSTEM
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANS
PHOSPHOLIPIDS
RADIOISOTOPES
RADIORECEPTOR ASSAY
RATS
RODENTS
SCORPIONS
SODIUM
SODIUM 22
SODIUM ISOTOPES
TOXIC MATERIALS
TOXINS
TRACER TECHNIQUES
VERTEBRATES
YEARS LIVING RADIOISOTOPES