March 2017 | Volume 149, No. 3

Research Articles

• Research Articles

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    Doublet stimulation increases Ca²⁺ binding to troponin C to ensure rapid force development in skeletal muscle

    High-frequency paired stimuli used to initiate a tetanus result in increased force and rate of force development in skeletal muscle. Bakker et al. investigate this mechanism and find that doublet stimulation increases the amount of Ca²⁺ bound to troponin C, resulting in rapid force development.

    Anthony J. Bakker, Tanya R. Cully, Catherine D. Wingate, Christopher J. Barclay, Bradley S. Launikonis
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    Mechanisms creating transient and sustained photoresponses in mammalian retinal ganglion cells

    Visual stimuli of different frequencies are encoded in the retina using transient and sustained responses. Zhao et al. describe the different strategies that are used by four types of retinal ganglion cells to shape photoresponse kinetics.

    Xiwu Zhao, Aaron N. Reifler, Melanie M. Schroeder, Elizabeth R. Jaeckel, Andrew P. Chervenak, Kwoon Y. Wong
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    Electrostatic tuning of the pre- and post-hydrolytic open states in CFTR

    Gating of the CFTR channel is coupled to ATP hydrolysis such that two open states can be identified under certain conditions. Zhang and Hwang find that pore-lining mutations differentially affect the permeation properties of these open states and suggest that the internal vestibule expands upon ATP hydrolysis.

    Jingyao Zhang, Tzyh-Chang Hwang
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    Deletion of cytosolic gating ring decreases gate and voltage sensor coupling in BK channels

    Both cellular depolarization and intracellular Ca²⁺ can gate open large conductance Ca²⁺-activated K⁺ channels. Zhang et al. show that the intracellular gating ring, which forms the Ca²⁺-sensing machinery of the channel, is also required for activated voltage sensors to effectively gate open the pore.

    Guohui Zhang, Yanyan Geng, Yakang Jin, Jingyi Shi, Kelli McFarland, Karl L. Magleby, Lawrence Salkoff, Jianmin Cui
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    Regulation of Na⁺ channel inactivation by the DIII and DIV voltage-sensing domains

    Hsu et al. probe voltage-gated Na⁺ channels that are inactivation deficient with voltage-clamp fluorometry. They find that in the time domain of an action potential, the voltage-sensing domain (VSD) of domain IV regulates fast inactivation onset while the domain III VSD determines its recovery.

    Eric J. Hsu, Wandi Zhu, Angela R. Schubert, Taylor Voelker, Zoltan Varga, Jonathan R. Silva