KTX3, the kaliotoxin from Buthus occitanus tunetanus scorpion venom: one of an extensive family of peptidyl ligands of potassium channels.
A new ligand of the K+ channels sensitive to KTX was purified from the venom of Buthus occitanus tunetanus, using two steps of high-performance-liquid-chromatography and by following its ability to compete with [125I]-KTX for binding to the KTX receptor on rat brain synaptosomes. Amino-acid analysis, amino acid sequencing and mass spectroscopy defined this new ligand. KTX3, as a 37-amino acid peptide, with three disulfide bridges. Its sequence shares 76% identity with KTX. The main differences between the two peptides are in the N-terminal region and the residue position 34 located in the region involved in channel recognition. These differences may explain the 5-fold lower binding affinity of KTX3, IC50=50 pM, than KTX to rat brain synaptosomes. Specific antibodies raised against KTX (1-37) were not able to recognize KTX3.
Meki
A
A
Laboratoire de Biochimie, Ingénierie des Protéines, UMR 6560 du Centre National de la Recherche Scientifique, Faculté de Médecine Nord, Institut Fédératif Jean Roche, Université de la Méditérranée, Marseille, France.
Mansuelle
P
P
Laraba-Djebari
F
F
Oughideni
R
R
Rochat
H
H
Martin-Eauclaire
M F
MF
D000595:Amino Acid Sequence; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D002118:Calcium / Q000502:physiology; D002851:Chromatography, High Pressure Liquid; D066298:In Vitro Techniques; D007276:Injections, Intraventricular; D007457:Iodine Radioisotopes; D007928:Lethal Dose 50; D008024:Ligands; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000187:drug effects* / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D012604:Scorpion Venoms / Q000378:metabolism / Q000494:pharmacology* / Q000633:toxicity; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism
D007457:Iodine Radioisotopes; D008024:Ligands; D015221:Potassium Channels; D012604:Scorpion Venoms; C404938:kaliotoxin KTX(3); D002118:Calcium