SUBUNITS INTERACTION IN THE FUNCTION OF BK CHANNELS

描述（由申请人提供）：我们的长期目标是了解bk型电压和Ca2+激活的K+通道的生理和病理生理作用。BK通道调节Ca2+信号在许多组织中的生理过程，如肌肉收缩、肾功能和神经传递。这些通道由孔隙形成、电压和Ca2+感应组成，该亚基由单个Slo1基因和四种辅助亚基编码（1-4）。这些亚基中的每一个都以不同的特征和组织特异性表达调节Slo1通道的功能特性。因此，亚基有助于确定各种组织中BK通道的表型和生理作用。为了实现我们的长期目标，有必要研究Slo1与¿亚基之间相互作用的分子机制。先前的出版物和我们的初步数据表明，尽管所有四种类型的¿亚基具有相似的结构特征，但它们对Slo1通道的调制机制在两个关键方面有所不同：1)它们针对Slo1中对通道门控重要的不同分子成分和过程，2)它们具有不同的氨基酸或基序（活性位点），这对改变Slo1通道的门控至关重要。基于这些初步结果，我们将利用电生理学、诱变、化学修饰和动力学建模等方法来实现以下具体目标：1 .确定Slo1通道中¿亚基调制的分子靶点。2。确定三个亚基的活性位点。3。检查亚基是否影响膜跨越和细胞质结构域之间的相互作用，这对BK通道门控至关重要。Aim III将在Aim I和Aim II中研究的亚基关联与最近揭示的BK通道门控的结构机制之间建立联系。本研究将确定对BK通道门控重要的氨基酸和结构基序，并揭示Slo1和¿亚基之间相互作用的本质。这将为理解BK通道相关病理条件的分子基础奠定基础，如癫痫和高血压，并为其治疗提供靶点和理论依据。具有跨膜段的K+通道亚基，如KCNE家族和BK亚基，可以调节各自的a亚基的门控特性，这是这些通道生理作用的关键。我们的初步研究表明，其中一些亚基可能通过共同的机制影响通道门控。因此，本研究将为K+通道功能的这些常见机制提供见解。

DESCRIPTION (provided by applicant): Our long-term goal is to understand the physiological and pathophysiological role of the BK-type voltage and Ca2+-activated K+ channels. BK channels modulate physiological processes that involve Ca2+ signaling in many tissues, such as muscle contraction, renal function and neural transmission. These channels are composed of the pore-forming, voltage- and Ca2+ -sensing a subunit that is encoded by a single Slo1 gene and four types of auxiliary ¿ subunit (¿1-4). Each of these ¿ subunits modulates functional properties of the Slo1 channel with distinct characteristics and tissue-specific expression. Thus, ¿ subunits help to define the phenotypes and physiological roles of BK channels in various tissues. To achieve our long-term goal, it is necessary to study the molecular mechanism of the interaction between Slo1 and the ¿ subunits. Previous publications and our preliminary data demonstrate that, although all four types of ¿ subunit share similar structural features, the mechanisms of their modulation of Slo1 channels differ in two key aspects: 1) they target different molecular components and processes in Slo1 that are important in channel gating, and 2) they have different amino acids or motifs (active sites) that are critical for altering gating of Slo1 channels. Based on these preliminary results, we will use the methods of electrophysiology, mutagenesis, chemical modification and kinetic modeling to achieve the following specific aims: I. To identify the molecular targets of ¿ subunits modulation in Slo1 channels. II. To identify the active sites of ¿ subunits. III. To examine if ¿ subunits affect the interaction between the membrane-spanning and the cytosolic domains that is critical for BK channel gating. Aim III will establish a link between the ¿ subunit association, as studied in Aims I and II, with a structural mechanism of BK channel gating that has been revealed recently. This study will identify amino acids and structural motifs important for BK channel gating and reveal the nature of the interactions between Slo1 and ¿ subunits. It will lay the foundation for understanding the molecular basis of BK channel related pathological conditions, such as epilepsy and hypertension, and provide the target and rationale for their treatment. ¿ subunits of K+ channels with transmembrane segment, such as the KCNE family and BK ¿ subunits modulate the gating properties of their respective a subunits, which are key to the physiological roles of these channels. Our preliminary studies suggest that some of these ¿ subunits may affect channel gating through common mechanisms. Therefore, this study will provide insights to these common mechanisms of K+ channel function. PUBLIC HEALTH RELEVANCE: This study will identify amino acids and structural motifs important for BK channel gating and reveal the nature of the interactions between Slo1 and ¿ subunits. It will lay the foundation for understanding the molecular basis of BK channel related pathological conditions, such as epilepsy and hypertension, and provide the target and rationale for their treatment.