T-tubule depolarization-induced local events in the ryanodine receptor, as monitored with the fluorescent conformational probe incorporated by mediation of peptide A.
T-tubule depolarization-induced local events in the ryanodine receptor, as monitored with the fluorescent conformational probe incorporated by mediation of peptide A.
复制标题
T 管去极化诱导兰尼碱受体中的局部事件，通过肽 A 介导的荧光构象探针进行监测。
DOI：
10.1074/jbc.m102347200
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Ikemoto,Noriaki
中科院分区：
文献类型：
--
作者：
Yamamoto,Takeshi;Ikemoto,Noriaki
There is a considerable controversy about the postulated role of the Thr671–Leu690(peptide A) region of the dihydropyridine (DHP) receptor α1 II-III loop. Here we report that peptide A introduced the fluorescence probe methyl coumarin acetamido (MCA) in a well defined region of the ryanodine receptor (RyR), A-site, in a specific manner. Depolarization of the T-tubule moiety of the triad induced a rapid increase of the fluorescence intensity of the MCA attached to the A-site. Other RyR agonists, which activate the RyR without mediation of the DHP receptor (e.g.caffeine, polylysine, and peptide A), induced Ca2+release without producing such an MCA fluorescence increase. Both magnitudes of the fluorescence change and Ca2+release increased with the increase in the degree of T-tubule depolarization. MCA fluorescence increase at the A-site and subsequent sarcoplasmic reticulum Ca2+release were blocked by blocking of the DHP receptor-to-RyR communication. These results may be accounted for by two alternative models as follows. (a) Upon T-tubule depolarization a portion of the DHP receptor comes close to the RyR, forming a hydrophobic interface (within such an interface the A-site is located), or (b) T-tubule depolarization may produce a local conformational change in the A-site-containing region of the RyR that is not necessarily within the DHP receptor/RyR junction.
