A new class of scorpion toxin binding sites related to an A-type K+ channel: pharmacological characterization and localization in rat brain.
A new scorpion toxin (3751.8 Da) was isolated from the Buthus martensi venom, sequenced and chemically synthesized (sBmTX3). The A-type current of striatum neurons in culture completely disappeared when 1 microM sBmTX3 was applied (Kd=54 nM), whereas the sustained K+ current was unaffected. 125I-sBmTX3 specifically bound to rat brain synaptosomes (maximum binding=14 fmol x mg(-1) of protein, Kd=0.21 nM). A panel of toxins yet described as specific ligands for K+ channels were unable to compete with 125I-sBmTX3. A high density of 125I-sBmTX3 binding sites was found in the striatum, hippocampus, superior colliculus, and cerebellum in the adult rat brain.
Vacher
H
H
UMR 6560 CNRSUniversité de la Mediterranée, Faculté de Médecine Nord, Marseille, France.
Romi-Lebrun
R
R
Mourre
C
C
Lebrun
B
B
Kourrich
S
S
Masméjean
F
F
Nakajima
T
T
Legros
C
C
Crest
M
M
Bougis
P E
PE
Martin-Eauclaire
M F
MF
D000595:Amino Acid Sequence; D000818:Animals; D001345:Autoradiography; D001667:Binding, Competitive; D002478:Cells, Cultured; D015640:Ion Channel Gating / Q000187:drug effects; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017072:Neostriatum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009498:Neurotoxins / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012604:Scorpion Venoms / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*
D009498:Neurotoxins; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D012604:Scorpion Venoms