Imperatoxin A, a Cell-Penetrating Peptide from Scorpion Venom, as a Probe of Ca-Release Channels/Ryanodine Receptors.
Imperatoxin A, a Cell-Penetrating Peptide from Scorpion Venom, as a Probe of Ca-Release Channels/Ryanodine Receptors.
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DOI：
10.3390/ph3041093
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发表时间：
2010-04-01
期刊：
影响因子：
--
通讯作者：
Valdivia HH
中科院分区：
文献类型：
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作者：
Gurrola GB;Capes EM;Zamudio FZ;Possani LD;Valdivia HH
蝎毒中含有丰富的离子通道修饰肽，是研究离子通道结构与功能关系的重要探针。我们以前分离的imperatoxin A（IpTxa），3.7 kDa的肽激活剂的钙释放通道/ryanodine受体（RyRs）和钙蛋白家族的蝎子肽的创始成员。IpTxa折叠成紧密的、大部分疏水的分子，在分子的一侧具有一簇带正电荷的碱性残基，其可能与细胞膜的磷脂相互作用。为了研究IpTxa是否渗透到细胞外膜并靶向体内RyRs，我们在完整的心肌细胞上灌注IpTxa，同时记录场刺激的细胞内Ca 2+瞬变。为了进一步研究毒素的细胞穿透能力，我们制备了IpTxa的巯基化荧光衍生物。生物活性和光谱特性表明，这些衍生物对RyR保持高亲和力，活性仅比天然IpTxa低5至10倍。我们的研究结果表明，IpTxa是能够穿越细胞膜，改变释放的Ca 2+在体内，并有能力携带一个大的，膜不渗透的货物跨质膜，一个令人兴奋的发现与新的药物输送的影响。
Scorpion venoms are rich in ion channel-modifying peptides, which have proven to be invaluable probes of ion channel structure-function relationship. We previously isolated imperatoxin A (IpTxa), a 3.7 kDa peptide activator of Ca2+-release channels/ryanodine receptors (RyRs) and founding member of the calcin family of scorpion peptides. IpTxa folds into a compact, mostly hydrophobic molecule with a cluster of positively-charged, basic residues polarized on one side of the molecule that possibly interacts with the phospholipids of cell membranes. To investigate whether IpTxa permeates external cellular membranes and targets RyRs in vivo, we perfused IpTxa on intact cardiomyocytes while recording field-stimulated intracellular Ca2+ transients. To further investigate the cell-penetrating capabilities of the toxin, we prepared thiolated, fluorescent derivatives of IpTxa. Biological activity and spectroscopic properties indicate that these derivatives retain high affinity for RyRs and are only 5- to 10-fold less active than native IpTxa. Our results demonstrate that IpTxa is capable of crossing cell membranes to alter the release of Ca2+ in vivo, and has the capacity to carry a large, membrane-impermeable cargo across the plasma membrane, a finding with exciting implications for novel drug delivery.