BK channel regulation by auxiliary LRR proteins

辅助 LRR 蛋白对 BK 通道的调节

• 批准号: 8849512
• 负责人: Jiusheng Yan
• 金额: $ 34.56万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8849512
• 关键词: Amino Acids; Applications Grants; Auditory; Biochemical; Biological; Brain region; Calcium; Cells; Chimera organism; Consensus; Coupling; Cysteine; Dependence; Disulfide Linkage; Docking; Elements; Family; Frequencies; Gated Ion Channel; Hair Cells; Hormones; Human; Human Cell Line; Hydrophobic Interactions; In Situ; LIM Domain; Leucine-Rich Repeat; Maps; Membrane Proteins; Modification; Molecular; Molecular Profiling; Mutation; N-Glycosylation Site; Nature; Neurons; Oxidation-Reduction; Pattern; Phosphorylation; Physiological; Physiological Processes; Post-Translational Protein Processing; Post-Translational Regulation; Potassium; Potassium Channel; Property; Proteins; Reagent; Regulation; Research; Rest; Scanning; Side; Site; Site-Directed Mutagenesis; Smooth Muscle; Structural Models; Surface; Tertiary Protein Structure; Therapeutic; Time; Tissues; base; cell type; crosslink; design; extracellular; glycosylation; human tissue; large-conductance calcium-activated potassium channels; leucine-rich repeat protein; member; neurotransmitter release; novel; paralogous gene; research study; sensor; voltage

DESCRIPTION (provided by applicant): The large conductance, calcium- and voltage-activated potassium (BK) channel is a unique member of the potassium channel family, which has the largest single channel conductance and is dually activated by voltage and cytosolic free Ca2+. BK channels consist of the pore-forming, voltage- and Ca2+-sensing α-subunits (BKα) either alone or in association with the tissue-specific regulatory subunits including the four previously known ß-subunits. We recently identified a novel BK channel auxiliary subunit, a leucine-rich repeat (LRR) containing membrane protein LRRC26, which causes an unprecedented large negative shift (~ -150 mV) in voltage dependence of channel activation by greatly enhancing the allosteric coupling between the voltage-sensor activation and the channel's closed-open transition, allowing BK channel activation at even near resting voltages and calcium levels in excitable and non-excitable cells. We have additionally identified three LRRC26- like paralogous proteins that modify the BK channel's voltage dependence of activation to different extents. LRRC26 and its paralogous LRR proteins are structurally and functionally distinct from the ß-subunits and are thus collectively designated as a family of BK channel γ-subunits. Three specific aims are designed to determine the physiological relevance and molecular mechanisms of BK channel regulation by these auxiliary γ-subunits: 1) determine the physiological and functional expression of the BK channel γ-subunits in human tissues and cells; 2) determine the biochemical mechanisms of BK channel modulation by the γ-subunits; 3) determine the posttranslational regulation of the γ-subunits' modulatory functions. Molecular biological, biochemical and electrophysiological experiments will be performed to achieve the proposed aims. Overall, the proposed research in this grant application is designed to systematically investigate these auxiliary LRR proteins for their physiological relevance and the underlying molecular mechanisms of channel modulation. The findings from the proposed studies will establish the physiological relevance of a new family of BK channel auxiliary subunits, and provide an in-depth understanding of the molecular mechanisms governing the LRRC26 and its paralogs' unique capacity in shifting the voltage dependence of a voltage-gated ion channel. These studies will thus offer a new molecular basis for an understanding and exploration of the ubiquitously expressed BK channel's diverse physiological functions, and help in creation of novel reagents and therapeutics to rationally manipulate BK channel activity.

描述(申请人提供)：大电导、钙和电压激活的钾通道(BK)是钾通道家族中唯一的成员，它具有最大的单通道电导，并由电压和胞内游离钙离子双重激活。BK通道由成孔、电压和钙离子敏感的α亚基(BKα)组成，或单独或与组织特异性调节亚基结合，包括四个已知的？亚基。我们最近发现了一个新的BK通道辅助亚基，一个富含亮氨酸重复序列(LRR)的膜蛋白LRRC26，它通过极大地增强电压传感器激活和通道闭合-开放转换之间的变构耦合，使BK通道在可兴奋和不可兴奋细胞中在接近静止电压和钙水平的情况下激活，从而导致通道激活的电压依赖性发生前所未有的大负移(~-150 mV)。此外，我们还鉴定了三种类似LRRC26的平行蛋白，它们在不同程度上改变了BK通道的激活的电压依赖性。LRRC26及其类似的LRR蛋白在结构和功能上都不同于BK通道γ-亚基，因此统称为BK通道LRR-亚基家族。为了确定这些辅助γ亚基调节BK通道的生理相关性和分子机制，我们设计了三个特定的目标：1)确定BK通道γ-亚基在人体组织和细胞中的生理和功能表达；2)确定γ-亚基调节BK通道的生化机制；3)确定γ-亚基的翻译后调节功能。将进行分子生物学、生化和电生理实验，以实现拟议的目标。总之，在这项拨款申请中提出的研究旨在系统地研究这些辅助LRR蛋白的生理相关性和通道调节的潜在分子机制。这些研究结果将建立一个新的BK通道辅助亚单位家族的生理学相关性，并为深入理解LRRC26及其类似物在改变电压门控离子通道的电压依赖性方面的独特能力提供分子机制。这些研究将为理解和探索普遍表达的BK通道的多种生理功能提供新的分子基础，并有助于创造新的试剂和治疗方法来合理地操纵BK通道的活性。