Interaction between the dihydropyridine receptor Ca2+ channel β-subunit and ryanodine receptor type 1 strengthens excitation-contraction coupling
Interaction between the dihydropyridine receptor Ca2+ channel β-subunit and ryanodine receptor type 1 strengthens excitation-contraction coupling
复制标题
DOI：
10.1073/pnas.0504334102
复制
发表时间：
2005-12-27
影响因子：
11.1
通讯作者：
Coronado, R
中科院分区：
文献类型：
--
作者：
Cheng, WJ;Altafaj, X;Coronado, R
以前的研究表明，骨骼二氢吡啶受体(DHPR)孔孔亚单位Cav1.1(α1s)与Ryr1(RyR1)物理上相互作用，分子信号从α15传递到RyR1，触发兴奋-收缩(EC)耦合。我们发现，骨骼DHPR的β-亚基也与RyR1结合并参与这一信号传递过程。DHPRβ1a亚基的一个新的结合位点被定位在RyR1的M-3201到W-3661区域。体外结合实验表明，相互作用的强度受(KKKRR)-K-3495R-3502，一簇带正电荷的残基控制。研究了(KKKRR)-K-3495_R-3502簇突变的RyR1在异常肌管中骨架型EC偶联的表型表达。结果表明，电荷中和或缺失严重抑制了RyR1介导的与DHPR电压依赖激活相耦合的钙瞬变的幅度。同时，肌浆网钙离子含量不受影响，DHPR钙电流的幅度和激活动力学略有改变。数据表明，DHPRβ亚基与α1S一样，与RyR1直接相互作用，对于产生与膜去极化耦合的高速钙信号至关重要。这些发现表明，骨骼肌中的EC偶联涉及至少两个DHPR亚单位的相互作用，即α1s和β1a，它们可能与RyR1的不同结构域相互作用。
Previous studies have shown that the skeletal dihydropyridine receptor (DHPR) pore subunit Cav1.1 (alpha 1S) physically interacts with ryanodine receptor type 1 (RyR1), and a molecular signal is transmitted from alpha 15 to RyR1 to trigger excitation-contraction (EC) coupling. We show that the beta-subunit of the skeletal DHPR also binds RyR1 and participates in this signaling process. A novel binding site for the DHPR beta 1a-subunit was mapped to the M-3201 to W-3661 region of RyR1. In vitro binding experiments showed that the strength of the interaction is controlled by (KKKRR)-K-3495 _ _ R-3502, a cluster of positively charged residues. Phenotypic expression of skeletal-type EC coupling by RyR1 with mutations in the (KKKRR)-K-3495 _ _ R-3502 cluster was evaluated in dyspedic myotubes. The results indicated that charge neutralization or deletion severely depressed the magnitude of RyR1-mediated Ca2+ transients coupled to voltage-dependent activation of the DHPR. Meantime the Ca2+ content of the sarcoplasmic reticulum was not affected, and the amplitude and activation kinetics of the DHPR Ca2+ currents were slightly affected. The data show that the DHPR beta-subunit, like alpha 1S, interacts directly with RyR1 and is critical for the generation of high-speed Ca2+ signals coupled to membrane depolarization. These findings indicate that EC coupling in skeletal muscle involves the interplay of at least two subunits of the DHPR, namely alpha 1S and beta 1a, interacting with possibly different domains of RyR1.