Pombe Cdc15 homology (PCH) proteins play an important role in a variety of actin-based processes, including clathrin-mediated endocytosis (CME). The defining feature of the PCH proteins is an evolutionarily conserved EFC/F-BAR domain for membrane association and tubulation. In the present study, we solved the crystal structures of the EFC domains of human FBP17 and CIP4. The structures revealed a gently curved helical-bundle dimer of approximately 220 A in length, which forms filaments through end-to-end interactions in the crystals. The curved EFC dimer fits a tubular membrane with an approximately 600 A diameter. We subsequently proposed a model in which the curved EFC filament drives tubulation. In fact, striation of tubular membranes was observed by phase-contrast cryo-transmission electron microscopy, and mutations that impaired filament formation also impaired membrane tubulation and cell membrane invagination. Furthermore, FBP17 is recruited to clathrin-coated pits in the late stage of CME, indicating its physiological role.

Surface modification by poly(ethylene glycol) (PEG) onto gene carrier prepared through the electrostatic assembly of pDNA and polycation (polyplex) is a widely acknowledged strategy to advance their systemic application. In this regard, PEG crowdedness on the polyplex surface should give important contribution in determining blood circulation property; however its accurate quantification has never been demonstrated. We report here the first successful determination of PEG crowdedness for PEGylated polyplexes (polyplex micelle) formed from PEG–poly(l-lysine) block copolymers (PEG–PLys) and plasmid DNA (pDNA). Tethered PEG chains were found to adopt mushroom and even squeezed conformation by modulating PEG crowdedness through PLys segment length. Energetic analysis was conducted on the polyplex micelle to elucidate effect of PEG crowdedness on shape and clarify its essential role in regulating packaging structure of pDNA within the polyplex micelle. Furthermore, the PEG crowdedness significantly correlated to blood retention profile, approving its critical role on both shape and systemic circulation property.

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As electrolytes for sodium secondary batteries operating over a wide temperature range, Na[FSA]-[C 3 C 1 pyrr][FSA] (FSA = bis(fluorosulfonyl)amide, C 3 C 1 pyrr = N-methyl-Npropylpyrrolidinium) ionic liquids have been investigated. The effects of Na ion concentration (0-60 mol% Na[FSA]) and operation temperature (253-363 K) on the viscosity and ioncic conductivity and charge-discharge performance of Na/Na[FSA]-[C 3 C 1 pyrr][FSA]/NaCrO 2 cells are studied. Results show that Na ion concentration strongly affects the rate capability of the cells, and that the best rate capability at 363 K is obtained at 40 mol% Na [FSA]. The 2 operation temperature also significantly influences the charge-discharge performance, especially at low temperatures. At operation temperatures below 273 K, 25 mol% Na[FSA] is found to be the optimum Na ion concentration. There exist different optimum ranges of Na ion concentration depending on the operation temperatures.