Meki A, Mansuelle P, Laraba-Djebari F, Oughideni R, Rochat H, Martin-Eauclaire M F
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.
Toxicon. 2000 Jan;38(1):105-11. doi: 10.1016/s0041-0101(99)00137-3.
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.
利用两步高效液相色谱法，并依据其与[125I]-KTX竞争结合大鼠脑突触体上KTX受体的能力，从北非黄肥尾蝎毒液中纯化出一种对KTX敏感的钾离子通道新配体。通过氨基酸分析、氨基酸测序和质谱确定了这种新配体KTX3，它是一种含有三个二硫键的37个氨基酸的肽。其序列与KTX有76%的同一性。这两种肽的主要差异在于N端区域以及位于通道识别相关区域的第34位残基。这些差异可能解释了KTX3（IC50 = 50 pM）对大鼠脑突触体的结合亲和力比KTX低5倍的原因。针对KTX（1 - 37）产生的特异性抗体无法识别KTX3。
