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Ca 2+激活的K+通道的生理和病理生理作用。BK通道调节许多组织中涉及Ca 2+信号的生理过程，如肌肉收缩、肾功能和神经传递。这些通道由单个Slo 1基因编码的成孔、电压和Ca 2+敏感亚基和四种类型的辅助亚基（<$1 -4）组成。这些亚基中的每一个都以不同的特征和组织特异性表达调节Slo 1通道的功能特性。因此，亚基有助于确定BK通道在各种组织中的表型和生理作用。为了实现我们的长期目标，有必要研究Slo 1和<$亚基之间相互作用的分子机制。以前的出版物和我们的初步数据表明，虽然所有四种类型的亚基具有相似的结构特征，但它们对Slo 1通道的调节机制在两个关键方面有所不同：1）它们靶向Slo 1中在通道门控中重要的不同分子组分和过程，和2）它们具有不同的氨基酸或基序（活性位点），这些氨基酸或基序对于改变Slo 1通道的门控至关重要。在此基础上，我们将采用电生理、诱变、化学修饰和动力学模拟等方法，实现以下具体目标：确定Slo 1通道中亚基调节的分子靶点。二.确定亚基的活性位点。三.检查亚基是否影响跨膜和胞质结构域之间的相互作用，这对BK通道门控至关重要。目的III将建立一个链接之间的亚基协会，研究目的I和II，与BK通道门控的结构机制，最近已经揭示。这项研究将确定对BK通道门控重要的氨基酸和结构基序，并揭示Slo 1和亚基之间相互作用的性质。这将为了解BK通道相关病理状态如癫痫和高血压的分子基础奠定基础，并为其治疗提供靶点和理论依据。具有跨膜段的K+通道的<$亚基，如KCNE家族和BK <$亚基调节其各自的α亚基的门控特性，这是这些通道的生理作用的关键。我们的初步研究表明，这些亚基中的一些可能通过共同的机制影响通道门控。因此，本研究将为这些常见的K+通道功能机制提供见解。 公共卫生相关性：这项研究将确定对BK通道门控重要的氨基酸和结构基序，并揭示Slo 1和亚基之间相互作用的性质。这将为了解BK通道相关病理状态如癫痫和高血压的分子基础奠定基础，并为其治疗提供靶点和理论依据。

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.