Interaction of the Lys(3614)-Asn(3643) calmodulin-binding domain with the Cys(4114)-Asn(4142) region of the type 1 ryanodine receptor is involved in the mechanism of Ca2+/agonist-induced channel activation.
Interaction of the Lys(3614)-Asn(3643) calmodulin-binding domain with the Cys(4114)-Asn(4142) region of the type 1 ryanodine receptor is involved in the mechanism of Ca2+/agonist-induced channel activation.
复制标题
Lys(3614)-Asn(3643) 钙调蛋白结合域与 1 型兰尼碱受体的 Cys(4114)-Asn(4142) 区域的相互作用参与 Ca2/激动剂诱导的通道激活机制。
DOI：
10.1042/bj20071375
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Ikemoto,Noriaki
中科院分区：
文献类型：
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作者：
Gangopadhyay,JayaP;Ikemoto,Noriaki
In the present study we show that the interaction of the CaM (calmodulin)-binding domain (Lys3614–Asn3643) with the Cys4114–Asn4142region (a region included in the CaM-like domain) serves as an intrinsic regulator of the RyR1 (type-1 ryanodine receptor). We tested the effects of antibodies raised against the two putative key regions of RyR1 [anti-(Lys3614–Asn3643) and anti-(Cys4114–Asn4142) antibodies]. Both antibodies produced significant inhibition of [3H]ryanodine-binding activity of RyR1. This suggests that the inter-domain interaction between the two domains, Lys3614–Asn3643and Cys4114–Asn4142, activates the channel, and that the binding of antibody to either side of the interacting domain pair interfered with the formation of a ‘channel-activation link’ between the two regions. In order to spectroscopically monitor the mode of interaction of these domains, the site of inter-domain interaction was fluorescently labelled with MCA [(7-methoxycoumarin-4-yl)acetyl] in a site-directed manner. The accessibility of the bound MCA to a large molecular mass fluorescence quencher, BSA-QSY (namely, the size of a gap between the interacting domains) decreased with an increase of [Ca2+] in a range of 0.03–2.0 μM, as determined by Stern–Volmer fluorescence quenching analysis. The Ca2+-dependent decrease in the quencher accessibility was more pronounced in the presence of 150 μM 4-CmC (4-chlorometacresol), and was reversed by 1 mM Mg2+(a well-known inhibitor of Ca2+/agonist-induced channel activation). These results suggest that the Lys3614–Asn3643and Cys4114–Asn4142regions of RyR1 interact with each other in a Ca2+- and agonist-dependent manner, and this serves as a mechanism of Ca2+- and agonist-dependent activation of the RyR1 Ca2+channel.
