Zamudio F Z, Gurrola G B, Arévalo C, Sreekumar R, Walker J W, Valdivia H H, Possani L D
Department of Molecular Recognition and Structural Biology, National Autonomous University of Mexico, Cuernavaca, Morelos.
FEBS Lett. 1997 Apr 1;405(3):385-9. doi: 10.1016/s0014-5793(97)00227-5.
We present the complete amino acid sequence of Imperatoxin A (IpTx(a)), a 33-amino-acid peptide from the venom of the scorpion P. imperator which activates Ca2+ release channels/ryanodine receptors (RyR) of sarcoplasmic reticulum (SR). The amino acid sequence of IpTx(a) shows no homology to any scorpion toxin so far described, but shares some homology to the amino acid sequence of Tx2-9 and agelenin, two spider toxins that target neuronal P-type Ca2+ channels. We also describe the total synthesis of IpTx(a) and demonstrate that it efficiently activates RyRs with potency and affinity identical to those of native IpTx(a). The use of synthetic IpTx(a) should help in the identification of the structural motifs of RyR critical for channel gating.
我们展示了帝王毒素A（IpTx(a)）的完整氨基酸序列，这是一种来自帝王蝎毒液的33个氨基酸的肽，它可激活肌浆网（SR）的Ca2+释放通道/兰尼碱受体（RyR）。IpTx(a)的氨基酸序列与迄今描述的任何蝎毒素均无同源性，但与Tx2-9和蛛毒素（两种靶向神经元P型Ca2+通道的蜘蛛毒素）的氨基酸序列有一些同源性。我们还描述了IpTx(a)的全合成，并证明它能以与天然IpTx(a)相同的效力和亲和力有效激活RyRs。合成IpTx(a)的应用应有助于鉴定对通道门控至关重要的RyR结构基序。
