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首页> 外文期刊>Pfluegers Archiv: European Journal of Physiology >TRIC-B channels display labile gating: Evidence from the TRIC-A knockout mouse model
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TRIC-B channels display labile gating: Evidence from the TRIC-A knockout mouse model

机译：TRIC-B通道显示不稳定的门控：来自TRIC-A剔除小鼠模型的证据

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摘要

Sarcoplasmic/endoplasmic reticulum (SR) and nuclear membranes contain two related cation channels named TRIC-A and TRIC-B. In many tissues, both subtypes are co-expressed, making it impossible to distinguish the distinct single-channel properties of each subtype. We therefore incorporated skeletal muscle SR vesicles derived from Tric-a-knockout mice into bilayers in order to characterise the biophysical properties of native TRIC-B without possible misclassification of the channels as TRIC-A, and without potential distortion of functional properties by detergent purification protocols. The native TRIC-B channels were ideally selective for cations. In symmetrical 210 mM K +, the maximum (full) open channel level (199 pS) was equivalent to that observed when wild-type SR vesicles were incorporated into bilayers. Analysis of TRIC-B gating revealed complex and variable behaviour. Four main sub-conductance levels were observed at approximately 80 % (161 pS), 60 % (123 pS), 46 % (93 pS), and 30 % (60 pS) of the full open state. Seventy-five percent of the channels were voltage sensitive with Po being markedly reduced at negative holding potentials. The frequent, rapid transitions between TRIC-B sub-conductance states prevented development of reliable gating models using conventional single-channel analysis. Instead, we used mean-variance plots to highlight key features of TRIC-B gating in a more accurate and visually useful manner. Our study provides the first biophysical characterisation of native TRIC-B channels and indicates that this channel would be suited to provide counter current in response to Ca2+ release from the SR. Further experiments are required to distinguish the distinct functional properties of TRIC-A and TRIC-B and understand their individual but complementary physiological roles.
机译：肌质/内质网（SR）和核膜包含两个相关的阳离子通道，称为TRIC-A和TRIC-B。在许多组织中，两种亚型都是共表达的，因此无法区分每种亚型的独特单通道特性。因此，我们将源自Tric-a敲除小鼠的骨骼肌SR囊泡并入双层，以表征天然TRIC-B的生物物理特性，而不会将通道错误分类为TRIC-A，并且不会因去污剂纯化而导致功能特性的潜在失真协议。天然的TRIC-B通道对阳离子具有理想的选择性。在对称的210 mM K +中，最大（完整）开放通道水平（199 pS）等于将野生型SR囊泡掺入双层时观察到的水平。对TRIC-B门控的分析揭示了复杂且可变的行为。在完全打开状态的大约80％（161 pS），60％（123 pS），46％（93 pS）和30％（60 pS）处观察到四个主要子导电水平。 75％的通道对电压敏感，在负保持电势下Po显着降低。 TRIC-B亚电导状态之间的频繁，快速过渡阻止了使用常规单通道分析方法开发可靠的门控模型。相反，我们使用均值方差图以更准确和视觉上有用的方式突出了TRIC-B门控的关键特征。我们的研究提供了天然TRIC-B通道的第一个生物物理特征，并表明该通道将适合提供响应从SR释放Ca2 +的逆流。需要进一步的实验来区分TRIC-A和TRIC-B的不同功能特性，并了解它们各自的但互补的生理作用。

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