Objective Junctophilin-2(JPH2)is an essential structural protein that maintains junctional membrane complexes(JMCs)in cardiomyocytes by tethering the plasma membrane to the sarcoplasmic reticulum,thereby facilitating ...Objective Junctophilin-2(JPH2)is an essential structural protein that maintains junctional membrane complexes(JMCs)in cardiomyocytes by tethering the plasma membrane to the sarcoplasmic reticulum,thereby facilitating excitationcontraction(E-C)coupling.Mutations in JPH2 have been associated with hypertrophic cardiomyopathy(HCM),but the molecular mechanisms governing its membrane-binding properties and the functional relevance of its membrane occupation and recognition nexus(MORN)repeat motifs remain incompletely understood.This study aimed to elucidate the structural basis of JPH2 membrane association and its implications for HCM pathogenesis.Methods A recombinant N-terminal fragment of mouse JPH2(residues 1-440),encompassing the MORN repeats and an adjacent helical region,was purified under near-physiological buffer conditions.X-ray crystallography was employed to determine the structure of the JPH2 MORN-Helix domain.Sequence conservation analysis across species and junctophilin isoforms was performed to assess the evolutionary conservation of key structural features.Functional membrane-binding assays were conducted using liposome co-sedimentation and cell-based localization studies in COS7 and HeLa cells.In addition,site-directed mutagenesis targeting positively charged residues and known HCM-associated mutations,including R347C,was used to evaluate their effects on membrane interaction and subcellular localization.Results The crystal structure of the mouse JPH2 MORN-Helix domain was resolved at 2.6Å,revealing a compact,elongated architecture consisting of multiple tandem MORN motifs arranged in a curved configuration,forming a continuous hydrophobic core stabilized by alternating aromatic residues.A C-terminalα-helix further reinforced structural integrity.Conservation analysis identified the inner groove of the MORN array as a highly conserved surface,suggesting its role as a protein-binding interface.A flexible linker segment enriched in positively charged residues,located adjacent to the MORN motifs,was found to mediate direct electrostatic interactions with negatively charged phospholipid membranes.Functional assays demonstrated that mutation of these basic residues impaired membrane association,while the HCM-linked R347C mutation completely abolished membrane localization in cellular assays,despite preserving the overall MORN-Helix fold in structural modeling.Conclusion This study provides structural insight into the membrane-binding mechanism of the cardiomyocyte-specific protein JPH2,highlighting the dual roles of its MORN-Helix domain in membrane anchoring and protein interactions.The findings clarify the structural basis for membrane targeting via a positively charged linker and demonstrate that disruption of this interaction—such as that caused by the R347C mutation—likely contributes to HCM pathogenesis.These results not only enhance current understanding of JPH2 function in cardiac E-C coupling but also offer a structural framework for future investigations into the assembly and regulation of JMCs in both physiological and disease contexts.展开更多
China’s efforts to develop Fengyun meteorological satellites have made major strides over the past 50 years,with the polar and geostationary meteorological satellite series achieving continuously stable operation to ...China’s efforts to develop Fengyun meteorological satellites have made major strides over the past 50 years,with the polar and geostationary meteorological satellite series achieving continuously stable operation to persistently provide data and product services globally.By the end of 2021,19 Chinese self-developed Fengyun meteorological satellites have been launched successfully.Seven of them are in operation at present,the data and products are widely applied to weather analysis,numerical weather forecasting and climate prediction,as well as environment and disaster monitoring.Since the last COSPAR report,FY-4B,the first new-generation operational geostationary satellite,and FY-3E,the first early-morning orbit satellite in China’s polar-orbiting meteorological satellite family have been launched in 2021.The characteristics of the two latest satellites and the instruments onboard are addressed in this report.The status of current Fengyun Satellites,product and data service and international cooperation and supporting activities has been introduced as well.展开更多
《新概念英语》是我国引进外国教材比较成功的一种,尤其第三册(技能的培养)部分,句型集中,词汇丰富,用法新颖。在此,笔者仅就 When 作为从属连词的妙用进行简要的介绍和粗浅的分析。众所周知,When 是一个简单从属连词(Simple Subordinat...《新概念英语》是我国引进外国教材比较成功的一种,尤其第三册(技能的培养)部分,句型集中,词汇丰富,用法新颖。在此,笔者仅就 When 作为从属连词的妙用进行简要的介绍和粗浅的分析。众所周知,When 是一个简单从属连词(Simple Subordinator),常见的语法意义是“当……的时候”,引导的从句往往作单纯的时间状语。如:展开更多
我们常会碰到这样的句子:1.He doesn’t speak the way I do.2.I don’t know the way you overcame all the difficulties. the way 用作“以某种方法(方式)”时本来要加介词in,但在现代英语中,省略介词in的情况却很普遍。例①中省略...我们常会碰到这样的句子:1.He doesn’t speak the way I do.2.I don’t know the way you overcame all the difficulties. the way 用作“以某种方法(方式)”时本来要加介词in,但在现代英语中,省略介词in的情况却很普遍。例①中省略介词后的the way在意思上相当于连词as(象……那样)。例②中省略介词后的the way就相当于how(如何)的意思了。再看下面的句子:展开更多
代词(pronoun)所代替的词,叫做代词的先行词(antecedent)。例如: I invited Joan,but she could not attend.(she代替Joan,Joan是she的先行词。) Because Joan and Mary were on vacation,I did not see them.(them的先行词是Joan and M...代词(pronoun)所代替的词,叫做代词的先行词(antecedent)。例如: I invited Joan,but she could not attend.(she代替Joan,Joan是she的先行词。) Because Joan and Mary were on vacation,I did not see them.(them的先行词是Joan and Mary.)展开更多
文摘Objective Junctophilin-2(JPH2)is an essential structural protein that maintains junctional membrane complexes(JMCs)in cardiomyocytes by tethering the plasma membrane to the sarcoplasmic reticulum,thereby facilitating excitationcontraction(E-C)coupling.Mutations in JPH2 have been associated with hypertrophic cardiomyopathy(HCM),but the molecular mechanisms governing its membrane-binding properties and the functional relevance of its membrane occupation and recognition nexus(MORN)repeat motifs remain incompletely understood.This study aimed to elucidate the structural basis of JPH2 membrane association and its implications for HCM pathogenesis.Methods A recombinant N-terminal fragment of mouse JPH2(residues 1-440),encompassing the MORN repeats and an adjacent helical region,was purified under near-physiological buffer conditions.X-ray crystallography was employed to determine the structure of the JPH2 MORN-Helix domain.Sequence conservation analysis across species and junctophilin isoforms was performed to assess the evolutionary conservation of key structural features.Functional membrane-binding assays were conducted using liposome co-sedimentation and cell-based localization studies in COS7 and HeLa cells.In addition,site-directed mutagenesis targeting positively charged residues and known HCM-associated mutations,including R347C,was used to evaluate their effects on membrane interaction and subcellular localization.Results The crystal structure of the mouse JPH2 MORN-Helix domain was resolved at 2.6Å,revealing a compact,elongated architecture consisting of multiple tandem MORN motifs arranged in a curved configuration,forming a continuous hydrophobic core stabilized by alternating aromatic residues.A C-terminalα-helix further reinforced structural integrity.Conservation analysis identified the inner groove of the MORN array as a highly conserved surface,suggesting its role as a protein-binding interface.A flexible linker segment enriched in positively charged residues,located adjacent to the MORN motifs,was found to mediate direct electrostatic interactions with negatively charged phospholipid membranes.Functional assays demonstrated that mutation of these basic residues impaired membrane association,while the HCM-linked R347C mutation completely abolished membrane localization in cellular assays,despite preserving the overall MORN-Helix fold in structural modeling.Conclusion This study provides structural insight into the membrane-binding mechanism of the cardiomyocyte-specific protein JPH2,highlighting the dual roles of its MORN-Helix domain in membrane anchoring and protein interactions.The findings clarify the structural basis for membrane targeting via a positively charged linker and demonstrate that disruption of this interaction—such as that caused by the R347C mutation—likely contributes to HCM pathogenesis.These results not only enhance current understanding of JPH2 function in cardiac E-C coupling but also offer a structural framework for future investigations into the assembly and regulation of JMCs in both physiological and disease contexts.
基金Supported by the National Key Research and Development Program of China(2018YFB0504900,2018YFB0504905)the National Project on Fengyun Meteorological Satellite Development。
文摘China’s efforts to develop Fengyun meteorological satellites have made major strides over the past 50 years,with the polar and geostationary meteorological satellite series achieving continuously stable operation to persistently provide data and product services globally.By the end of 2021,19 Chinese self-developed Fengyun meteorological satellites have been launched successfully.Seven of them are in operation at present,the data and products are widely applied to weather analysis,numerical weather forecasting and climate prediction,as well as environment and disaster monitoring.Since the last COSPAR report,FY-4B,the first new-generation operational geostationary satellite,and FY-3E,the first early-morning orbit satellite in China’s polar-orbiting meteorological satellite family have been launched in 2021.The characteristics of the two latest satellites and the instruments onboard are addressed in this report.The status of current Fengyun Satellites,product and data service and international cooperation and supporting activities has been introduced as well.
文摘《新概念英语》是我国引进外国教材比较成功的一种,尤其第三册(技能的培养)部分,句型集中,词汇丰富,用法新颖。在此,笔者仅就 When 作为从属连词的妙用进行简要的介绍和粗浅的分析。众所周知,When 是一个简单从属连词(Simple Subordinator),常见的语法意义是“当……的时候”,引导的从句往往作单纯的时间状语。如:
文摘我们常会碰到这样的句子:1.He doesn’t speak the way I do.2.I don’t know the way you overcame all the difficulties. the way 用作“以某种方法(方式)”时本来要加介词in,但在现代英语中,省略介词in的情况却很普遍。例①中省略介词后的the way在意思上相当于连词as(象……那样)。例②中省略介词后的the way就相当于how(如何)的意思了。再看下面的句子:
文摘代词(pronoun)所代替的词,叫做代词的先行词(antecedent)。例如: I invited Joan,but she could not attend.(she代替Joan,Joan是she的先行词。) Because Joan and Mary were on vacation,I did not see them.(them的先行词是Joan and Mary.)
