Voigt Andreas, Freund Romy, Heck Jennifer, Missler Markus, Obermair Gerald J, Thomas Ulrich, Heine Martin
Otto-von-Guericke-University of Magdeburg , Lehrstuhl Systemverfahrenstechnik, Universitätsplatz 2, Magdeburg D-39106, Germany.
Leibniz-Institute of Neurobiology , Research Group Molecular Physiology, Brenneckestrasse 6, Magdeburg D-39118, Germany.
Neurophotonics. 2016 Oct;3(4):041809. doi: 10.1117/1.NPh.3.4.041809. Epub 2016 Nov 3.
High voltage gated calcium channels (VGCCs) are composed of at least three subunits, one pore forming [Formula: see text]-subunit, an intracellular [Formula: see text]-variant, and a mostly extracellular [Formula: see text]-variant. Interactions between these subunits determine the kinetic properties of VGCCs. It is unclear whether these interactions are stable over time or rather transient. Here, we used single-molecule tracking to investigate the surface diffusion of [Formula: see text]- and [Formula: see text]-subunits at the cell surface. We found that [Formula: see text]-subunits show higher surface mobility than [Formula: see text]-subunits, and that they are only transiently confined together, suggesting a weak association between [Formula: see text]- and [Formula: see text]-subunits. Moreover, we observed that different [Formula: see text]-subunits engage in different degrees of association with the [Formula: see text]-subunit, revealing the tighter interaction of [Formula: see text] with [Formula: see text]. These data indicate a distinct regulation of the [Formula: see text] interaction in VGCC subtypes. We modeled their membrane dynamics in a Monte Carlo simulation using experimentally determined diffusion constants. Our modeling predicts that the ratio of associated [Formula: see text]- and [Formula: see text]-subunits mainly depends on their expression density and confinement in the membrane. Based on the different motilities of particular [Formula: see text]-subunit combinations, we propose that their dynamic assembly and disassembly represent an important mechanism to regulate the signaling properties of VGCC.
高压门控钙通道（VGCCs）至少由三个亚基组成，一个形成孔道的α1亚基、一个细胞内的β亚基变体，以及一个主要位于细胞外的α2δ亚基变体。这些亚基之间的相互作用决定了VGCCs的动力学特性。目前尚不清楚这些相互作用是随时间稳定存在还是短暂的。在这里，我们使用单分子追踪技术来研究α1和α2δ亚基在细胞表面的扩散。我们发现α1亚基比α2δ亚基表现出更高的表面迁移率，并且它们只是短暂地聚集在一起，这表明α1和α2δ亚基之间的结合较弱。此外，我们观察到不同的α2δ亚基与α1亚基的结合程度不同，揭示了α2δ1与α1的相互作用更紧密。这些数据表明VGCC亚型中α1相互作用存在明显的调控。我们使用实验确定的扩散常数在蒙特卡罗模拟中对它们的膜动力学进行建模。我们的模型预测，结合的α1和α2δ亚基的比例主要取决于它们在膜中的表达密度和受限程度。基于特定α1亚基组合的不同运动性，我们提出它们的动态组装和解离是调节VGCC信号特性的重要机制。
