Functional consequences of deleting the two C-terminal residues of the scorpion toxin BmTX3.
We deleted the two C-terminal residues of the scorpion toxin BmTx3, a peptidyl inhibitor of a transient A-type K(+) current in striatum neurons in culture, to assess their contribution to receptor recognition. The sBmTX3-delYP analog was shown to have a native-like structure in one-dimensional 1H-nuclear magnetic resonance (NMR) spectroscopy. We found that sBmTX3-delYP bound to its receptor less efficiently than the wild-type molecule (by a factor of about 10(5)) in binding assays with rat brain membranes, and that this molecule did not block the A-type K(+) current (at a concentration of 35 microM) in whole-cell patch clamp experiments with striatum neurons. Also, these results show that the A-type K(+) channel blocked by BmTX3 should have a canonical K(+) channel pore structure.
Vacher
Hélène
H
CNRS UMR 6560, Faculté de Médecine Nord, Institut Jean Roche, Université de la Mediterranée, Boulevard Pierre Dramard, 13916, Marseille Cedex 20, France.
Romi-Lebrun
Régine
R
Crest
Marcel
M
Masmejean
Frédérique
F
Bougis
Pierre E
PE
Darbon
Hervé
H
Martin-Eauclaire
Marie-France
MF
D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000737:chemistry; D051381:Rats; D012604:Scorpion Venoms / Q000737:chemistry / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism; D014443:Tyrosine / Q000737:chemistry
D015221:Potassium Channels; D012604:Scorpion Venoms; C418406:TX3 toxin, Buthus martensii; D014443:Tyrosine