Role of the Gln/Glu residues of trichocellins A-II/B-II in ion-channel formation in lipid membranes and catecholamine secretion from chromaffin cells.
Role of the Gln/Glu residues of trichocellins A-II/B-II in ion-channel formation in lipid membranes and catecholamine secretion from chromaffin cells.
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Trichocellins A-II/B-II 的 Gln/Glu 残基在脂膜离子通道形成和嗜铬细胞儿茶酚胺分泌中的作用。
DOI：
10.1016/s0005-2736(96)00260-x
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
T. Fujita
中科院分区：
文献类型：
--
作者：
S. Wada;A. Iida;K. Asami;E. Tachikawa;T. Fujita
Trichocellins（TC）A-II和B-II是从真菌绿色木霉（Trichoderma viride）的分生孢子分离的20个残基的肽酶，除了第18位的残基之外，具有相同的序列。发现这两种TC在双层脂质膜（BLM）中形成电压依赖性离子通道，并通过Ca 2+内流诱导牛肾上腺嗜铬细胞分泌儿茶酚胺。TC-A-II（Gln 18，neutral）比TC-B-II（Glu 18，charged）更有效地诱导BLM中的宏观电流和从嗜铬细胞分泌儿茶酚胺，表明Glu 18不利于BLM和嗜铬细胞膜中离子通道的形成。然而，单通道记录表明，TC-B-II形成更大的孔，具有更长的开放寿命比TC-A-II。这表明Glu在位置18处的带负电荷的羧基稳定较大的孔。Glu 18的负电荷对活性的影响通过使用含有Glu 18的甲酯的TC-B-II类似物来证实。
Trichocellins (TC) A-II and B-II, 20-residue peptaibols isolated from conidia of the fungus Trichoderma viride, have the same sequence except for the residue at position 18. Both TCs were found to form voltage-dependent ion-channels in bilayer lipid membranes (BLM) and to induce catecholamine secretion from bovine adrenal chromaffin cells through Ca2+influx. TC-A-II (Gln18, neutral) was more effective than TC-B-II (Glu18, charged) for macroscopic current induction in BLMs and for catecholamine secretion from chromaffin cells, suggesting that Glu18is unfavorable for the ion-channel formation in BLMs and chromaffin cell membranes. Nevertheless, single-channel recordings indicated that TC-B-II forms larger pores with longer open lifetimes than those of TC-A-II. This indicates that the negatively charged carboxyl group of Glu at position 18 stabilizes larger pores. The effects of the negative charge of Glu18on the activities were confirmed by the use of a TC-B-II analog containing the methyl ester of Glu18.