Characterization of the binding of the Ptychodiscus brevis neurotoxin T17 to sodium channels in rat brain synaptosomes

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:6709604

Poli, M A

The lipid-soluble polyether neurotoxins isolated from the marine dinoflagellate Ptychodiscus brevis (formerly Gymnodinium breve) have been determined to bind to a unique receptor site associated with the voltage-sensitive sodium channel in rat brain synaptosomes. Reduction of the C/sub 42/ aldehyde function of T34 to the alcohol function of T17 using NaB/sup 3/H/sub 4/ yielded /sup 3/H-T17 with a specific activity of 15 Ci;/mmol. Using this specific probe, binding to sodium channels was measured at 4/sup 0/CC, 22/sup 0/C, and 37/sup 0/C. Rosenthal analysis of the binding data yielded a K/sub d/ of 2.9 nM and B/sub max/ of 6.8 pmoles /sup 3/H-T17 per mg of synaptosomal protein at 4/sup 0/C. Both K/sub d/ and B/sub max/ were found to be temperature dependent. Depolarization of the synaptosomes by osmotic lysis resulted in the loss of 34% of the available receptor sites, with no decrease in binding affinity. Unlabeled T17, T34, and synthetic T17 (reduced T34) were equipotent in their ability to displace /sup 3/H-T17 from its specific receptor site. Competition experiments using natural toxin probes specific for sites I-IV on the voltage-sensitive sodium channel demonstrate that /sup 3/H-T17 does not bind to any of the previously-described neurotoxin receptor sites. A fifth site is proposed.

• Research Organization: Miami Univ., Coral Gables, FL (USA)
• OSTI ID: 6709604
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL COMPOUNDS
ANIMAL TISSUES
ANIMALS
ANTIGENS
BIOCHEMICAL REACTION KINETICS
BODY
BRAIN
CENTRAL NERVOUS SYSTEM
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
MATERIALS
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
NERVE TISSUE
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIORECEPTOR ASSAY
RATS
REACTION KINETICS
RECEPTORS
RODENTS
SODIUM COMPOUNDS
TISSUES
TOXIC MATERIALS
TOXINS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
UPTAKE
VERTEBRATES