As the major component of cell membranes, phosphatidylcholine (PC) is synthesized de novo in the Kennedy pathway and then undergoes extensive deacylation-reacylation remodeling via Lands' cycle. The ...re-acylation is catalyzed by lysophosphatidylcholine acyltransferase (LPCAT) and among the four LPCAT members in human, the LPCAT3 preferentially introduces polyunsaturated acyl onto the sn-2 position of lysophosphatidylcholine, thereby modulating the membrane fluidity and membrane protein functions therein. Combining the x-ray crystallography and the cryo-electron microscopy, we determined the structures of LPCAT3 in apo-, acyl donor-bound, and acyl receptor-bound states. A reaction chamber was revealed in the LPCAT3 structure where the lysophosphatidylcholine and arachidonoyl-CoA were positioned in two tunnels connected near to the catalytic center. A side pocket was found expanding the tunnel for the arachidonoyl CoA and holding the main body of arachidonoyl. The structural and functional analysis provides the basis for the re-acylation of lysophosphatidylcholine and the substrate preference during the reactions.
Abstract Anion exchanger 3 (AE3) is pivotal in regulating intracellular pH across excitable tissues, yet its structural intricacies and functional dynamics remain underexplored compared to other ...anion exchangers. This study unveils the structural insights into human AE3, including the cryo-electron microscopy structures for AE3 transmembrane domains (TMD) and a chimera combining AE3 N-terminal domain (NTD) with AE2 TMD (hAE3 NTD 2 TMD ). Our analyzes reveal a substrate binding site, an NTD-TMD interlock mechanism, and a preference for an outward-facing conformation. Unlike AE2, which has more robust acid-loading capabilities, AE3’s structure, including a less stable inward-facing conformation due to missing key NTD-TMD interactions, contributes to its moderated pH-modulating activity and increased sensitivity to the inhibitor DIDS. These structural differences underline AE3’s distinct functional roles in specific tissues and underscore the complex interplay between structural dynamics and functional specificity within the anion exchanger family, enhancing our understanding of the physiological and pathological roles of the anion exchanger family.
Abstract
The cell maintains its intracellular pH in a narrow physiological range and disrupting the pH-homeostasis could cause dysfunctional metabolic states. Anion exchanger 2 (AE2) works at high ...cellular pH to catalyze the exchange between the intracellular HCO
3
−
and extracellular Cl
−
, thereby maintaining the pH-homeostasis. Here, we determine the cryo-EM structures of human AE2 in five major operating states and one transitional hybrid state. Among those states, the AE2 shows the inward-facing, outward-facing, and intermediate conformations, as well as the substrate-binding pockets at two sides of the cell membrane. Furthermore, critical structural features were identified showing an interlock mechanism for interactions among the cytoplasmic N-terminal domain and the transmembrane domain and the self-inhibitory effect of the C-terminal loop. The structural and cell-based functional assay collectively demonstrate the dynamic process of the anion exchange across membranes and provide the structural basis for the pH-sensitive pH-rebalancing activity of AE2.
Retroperitoneal ectopic pregnancy (REP) is a rare type of pregnancy with retroperitoneal implantation of the embryo. Herein, we report a case of a 29‐year‐old female with REP admitted in our ...department. Moreover, we review the literatures published previously reporting REP with the aim to improve the understanding of diagnosis and treatment of REP.
The skin contains three primary layers: epidermis, dermis, and hypodermis. Separation of epidermal components from dermis (dermal-epidermal separation) is an important basic investigation technique ...for pharmacology, toxicology, and biology. There are different systems of epidermal separation, including typical methods of chemical, enzyme, heat, etc. Each approach has advantages versus disadvantages, and thus the appropriate method should be chosen for a given research question. Here we described the method of enzyme separation.
The skin contains three primary layers: epidermis, dermis, and hypodermis. Separation of epidermal components from the dermis (dermal-epidermal separation) is an important basic investigation ...technique for pharmacology, toxicology, and biology. There are different systems of epidermal separation, including typical methods of chemical, enzyme, heat, etc. Each approach has advantages versus disadvantages, and thus the appropriate method should be chosen for a given research question. Here we described the method of heat separation.
The skin contains three primary layers: epidermis, dermis, and hypodermis. Separation of epidermal components from dermis (dermal-epidermal separation) is an important basic investigation technique ...for pharmacology, toxicology, and biology. There are different systems of epidermal separation, including typical methods of chemical, enzyme, heat, etc. Each approach has advantages versus disadvantages, and thus the appropriate method should be chosen for a given research question. Here we described the method of chemical separation.
The cell maintains its intracellular pH in a narrow physiological range and disrupting the pH-homeostasis could cause dysfunctional metabolic states. Anion exchanger 2 (AE2) works at high cellular pH ...to catalyze the exchange between the intracellular HCO
and extracellular Cl
, thereby maintaining the pH-homeostasis. Here, we determine the cryo-EM structures of human AE2 in five major operating states and one transitional hybrid state. Among those states, the AE2 shows the inward-facing, outward-facing, and intermediate conformations, as well as the substrate-binding pockets at two sides of the cell membrane. Furthermore, critical structural features were identified showing an interlock mechanism for interactions among the cytoplasmic N-terminal domain and the transmembrane domain and the self-inhibitory effect of the C-terminal loop. The structural and cell-based functional assay collectively demonstrate the dynamic process of the anion exchange across membranes and provide the structural basis for the pH-sensitive pH-rebalancing activity of AE2.
The protection of blockchain wallet is the basis of secure transaction in blockchain. Private key is the core of wallet security. The private key cannot be protected based on a reliable third party. ...Therefore, the loss or theft of private key will lead to the loss of customer property. To solve this problem, a distributed protection and recovery mechanism is proposed. Every wallet private key is divided into multiple key fragments by threshold key mechanism according to the network scale. Even if the wallet is offline, the threshold number of holders holding key fragements from the wallet cooperates to distribute key fragments to new members, which keeps the update of key fragments synchronized. When the key is lost, the number of private key fragments exceeding the threshold of half the blockchain member scale can ensure the recovery of the private key. The dynamic threshold mechanism design makes the attacker must attack more than half of the members to steal the wallet private key successfully. The hash ba
背景与目的 厄洛替尼在NSCLC患者中已有广泛应用，并能使部分NSCLC患者明显获益。本研究探讨厄洛替尼单药一线或二、三线治疗晚期非小细胞肺癌的临床疗效及毒副反应。方法 研究对象为2007年6月-2008年8月接受过化疗或未化疗过的IIIb或IV期非小细胞肺癌患者，给予厄洛替尼口服150 mg/d，直至疾病进展，观察疗效及毒副反应。结果 ...共有42例患者入组，随访至2009年7月10日，中位随访期为17个月，依从性为100%。42例患者中CR 2.4%（1/42）、PR 35.8%（15/42）、SD 47.6%（20/42）、PD 14.3%（6/42）、疾病控制率（CR+PR+SD）85.7%；中位疾病进展时间和中位生存时间分别为7个月和12.2个月；1年肿瘤无进展生存率和1年生存率分别为29%和55%。毒副反应为痤疮样皮疹78.6%（33/42）、腹泻35.7%（15/42）、转氨酶升高7.1%（3/42）、急性间质性肺病2.4%（1/42）。结论 不管作为一线或者二、三线治疗，厄洛替尼治疗晚期非小细胞肺癌疗效较好，毒副反应轻微，临床获益率高，能明显改善患者的生活质量。 Background and objective Erlotinib has been used widely in non-small cell lung cancer (NSCLC), and a portion of patients can gain remarkable benefit. This aim of the study is to evaluate the response and the side effects of Erlotinib as the treatment in patients with advanced non-small cell lung cancer (NSCLC). Methods Total 14 NSCLC(IIIb or IV stage)patients, treated from June 2007 to July 2008, were enrolled in our study. Erlotinib was prescribed on the oral dose of 150 mg daily. The treatment response and side-effects were recorded. Patients were followed up. Kaplan-Meier method was used to perform survival analysis. Results Forty-two NSCLC patients were enrolled into the study and followed up until July 10, 2009. The median follow-up period was 16 months and the follow-up ratio was 100%. CR, PR, SD, PD were achieved 2.4% (1/42), 35.8% (15/42), 47.6% (20/42) and 14.3% (6/42), respectively. Disease control rate (DCR) was reported by 85.7%. Median time to progression and median overall survival period were 7 and 12.2 months, respectively. One year progression-free survival rate and 1-year overall survival rate were 29% and 55%, respectively. Adverse events included acneiform rash 78.6% (33/42), diarrhea 35.7% (15/42), hepatic dysfunction 7.1% (3/42) and acute interstitial lung disease 2.4% (1/42). Conclusion Erlotinib is an effective therapy for patients with advanced non-small cell lung cancer with acceptable side effects.
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