Shape, size, and distribution of Ca2+ release units and couplons in skeletal and cardiac muscles
Shape, size, and distribution of Ca2+ release units and couplons in skeletal and cardiac muscles
复制标题
DOI：
10.1016/s0006-3495(99)77000-1
复制
发表时间：
1999-09-01
影响因子：
3.4
通讯作者：
Ramesh, V
中科院分区：
文献类型：
--
作者：
Franzini-Armstrong, C;Protasi, F;Ramesh, V
骨骼肌和心肌中的兴奋 - 收缩偶联（e - c偶联）涉及肌浆网（SR）的特化连接区域与外部膜（表面膜或横小管（T小管））之间的相互作用。这种相互作用发生在名为钙释放单元（CRUs）的特殊结构处。钙释放单元包含两种对e - c偶联至关重要的蛋白质：二氢吡啶受体（DHPRs），即外部膜的L型Ca²⁺通道；以及兰尼碱受体（RyRs），即肌浆网的Ca²⁺释放通道。心肌中的特殊钙释放单元由带有兰尼碱受体且不与外部膜相关联的肌浆网区域构成（小泡状和扩展连接肌浆网或EjSR）。钙释放单元内兰尼碱受体和二氢吡啶受体的功能组合被称为偶联子，该术语也被宽泛地应用于心肌的EjSR。了解偶联子的结构、几何形状和排列对于理解肌肉激活过程中Ca²⁺释放的机制至关重要。本文汇集了多种骨骼肌和心肌中偶联子的定量数据，这对模拟钙释放事件（宏观和微观的“钙火花”）很有用。
Excitation contraction (e-c) coupling in skeletal and cardiac muscles involves an interaction between specialized junctional domains of the sarcoplasmic reticulum (SR) and of exterior membranes (either surface membrane or transverse (T) tubules). This interaction occurs at special structures named calcium release units (CRUs). CRUs contain two proteins essential to e-c coupling: dihydropyridine receptors (DHPRs), L-type Ca2+ channels of exterior membranes; and ryanodine receptors (RyRs), the Ca2+ release channels of the SR. Special CRUs in cardiac muscle are constituted by SR domains bearing RyRs that are not associated with exterior membranes (the corbular and extended junctional SR or EjSR). Functional groupings of RyRs and DHPRs within calcium release units have been named couplons, and the term is also loosely applied to the EjSR of cardiac muscle. Knowledge of the structure, geometry, and disposition of couplons is essential to understand the mechanism of Ca2+ release during muscle activation. This paper presents a compilation of quantitative data on couplons in a variety of skeletal and cardiac muscles, which is useful in modeling calcium release events, both macroscopic and microscopic ("sparks").