Identification of a Guanine Nucleotide Exchange Factor for Arf3, the Yeast Orthologue of Mammalian Arf6

Small G proteins of the Arf and Rab families are fundamental to the organisation and activity of intracellular membranes. One of the most well characterised of these G proteins is mammalian Arf6, a protein that participates in many cellular processes including endocytosis, actin remodelling and cell adhesion. Exchange of GDP for GTP on Arf6 is performed by a variety of guanine nucleotide exchange factors (GEFs), principally of the cytohesin (PSCD) and EFA6 (PSD) families. In this paper we describe the characterisation of a GEF for the yeast orthologue of Arf6, Arf3, which we have named Yel1 (yeast EFA6-like-1) using yeast genetics, fluorescence microscopy and in vitro nucleotide exchange assays. Yel1 appears structurally related to the EFA6 family of GEFs, having an N-terminal Sec7 domain and C-terminal PH and coiled-coil domains. We find that Yel1 is constitutively targeted to regions of polarised growth in yeast, where it co-localises with Arf3. Moreover the Sec7 domain of Yel1 is required for its membrane targeting and for that of Arf3. Finally we show that the isolated Yel1 Sec7 domain strongly stimulates nucleotide exchange activity specifically on Arf3 in vitro

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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Crystalline morphologies at the surface of PET/PEN random copolymer films

A series of PET (poly(ethylene terephthalate))/PEN (poly(ethylene 2,6‐naphthalate)) copolyesters were synthesized by molten transesterification, and the surface crystallization behavior of their thin films investigated by atomic force microscope with an in situ heating stage. Force‐distance measurements detected a surface glass transition (T gS) of the copolymers several tens of degrees below their bulk glass transition (T gB) obtained by differential scanning calorimeter. The surface crystalline morphologies as a function of annealing temperature and film thickness were summarized as surface morphology diagrams. The surface crystallization temperature (T cS) was found to be several degrees lower than the bulk crystallization (T cB), and the films thinner than ~100 nm showed significant increase in T cB. The lamellar crystalline morphology of copolymers with high randomness and short sequence length deviated from that of the homopolymers, reflecting the composition and degree of randomness. Highly random PET/PEN = 75/25 wt% copolymers exhibited unique lamellar curvature with arbitrary growth directions. Sharp boundaries between the crystals and amorphous suggested an absence of large amounts of rejected material at the growth front. In the case of copolymers with high randomness and short sequence length, no bulk crystallization morphology was observed even at 190°C, with the relatively thick surface crystalline layer totally covering the emergence of any bulk crystals. </p

Crystalline morphologies at the surface of PET/PEN random copolymer films

A series of PET (poly(ethylene terephthalate))/PEN (poly(ethylene 2,6‐naphthalate)) copolyesters were synthesized by molten transesterification, and the surface crystallization behavior of their thin films investigated by atomic force microscope with an in situ heating stage. Force‐distance measurements detected a surface glass transition (T gS) of the copolymers several tens of degrees below their bulk glass transition (T gB) obtained by differential scanning calorimeter. The surface crystalline morphologies as a function of annealing temperature and film thickness were summarized as surface morphology diagrams. The surface crystallization temperature (T cS) was found to be several degrees lower than the bulk crystallization (T cB), and the films thinner than ~100 nm showed significant increase in T cB. The lamellar crystalline morphology of copolymers with high randomness and short sequence length deviated from that of the homopolymers, reflecting the composition and degree of randomness. Highly random PET/PEN = 75/25 wt% copolymers exhibited unique lamellar curvature with arbitrary growth directions. Sharp boundaries between the crystals and amorphous suggested an absence of large amounts of rejected material at the growth front. In the case of copolymers with high randomness and short sequence length, no bulk crystallization morphology was observed even at 190°C, with the relatively thick surface crystalline layer totally covering the emergence of any bulk crystals