Search results for "fusion"

Mg2+-binding shifts the IM30 activity from membrane protection to membrane destabilization

2020

ABSTRACTThe inner membrane-associated protein of 30 kDa (IM30) is essential in chloroplasts and cyanobacteria. The spatio-temporal cellular localization of the protein appears to be highly dynamic and triggered by internal as well as external stimuli, mainly light intensity. A soluble fraction of the protein is localized in the cyanobacterial cytoplasm or the chloroplast stroma, respectively. Additionally, the protein attaches to the thylakoid membrane as well as to the chloroplast inner envelope or the cyanobacterial cytoplasmic membrane, respectively, especially under conditions of membrane stress. IM30 is involved in thylakoid membrane biogenesis and/or maintenance, where it either stabi…

IM30 triggers membrane fusion in cyanobacteria and chloroplasts

2015

The thylakoid membrane of chloroplasts and cyanobacteria is a unique internal membrane system harbouring the complexes of the photosynthetic electron transfer chain. Despite their apparent importance, little is known about the biogenesis and maintenance of thylakoid membranes. Although membrane fusion events are essential for the formation of thylakoid membranes, proteins involved in membrane fusion have yet to be identified in photosynthetic cells or organelles. Here we show that IM30, a conserved chloroplast and cyanobacterial protein of approximately 30 kDa binds as an oligomeric ring in a well-defined geometry specifically to membranes containing anionic lipids. Triggered by Mg2+, membr…

The redox state regulates RNA degradation in the chloroplast of Chlamydomonas reinhardtii.

1999

Abstract A Chlamydomonas reinhardtii chloroplast transformant, designated MU7, carrying a chimeric (rbcL promoter: β-glucuronidase [GUS]:psaB 3′ end) gene whose transcripts have been found previously to be unstable in light (half-life of 20 min in light as opposed to a half-life of 5 h in the dark), was used to study the role of electron transport and of the redox state in the degradation of chloroplast transcripts in the light. Blocking photosynthetic electron transport with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) prevented the light-dependent breakdown of the pool of GUS transcripts in MU7 cells. Diamide, an oxidizing agent, caused a measurable delay in the degradation of GUS trans…

Down-regulation of transcription factors AP-1, Sp-1, and NF-kappa B precedes myocyte differentiation.

1996

Terminal differentiation of myocytes involves withdrawal from the cell cycle, induction of myogenin expression, and finally formation of myotubes. To study the factors that regulate the initial phase of muscle differentiation, we analyzed the binding activities of transcription factors AP-1, Sp-1, and NF-kappa B in L6, C2C12, and rhabdomyosarcoma BA-Han-1C cells. Temporal changes in transcription factor binding activities were compared to the activation of myogenin promoter-driven CAT reporter gene and the expression level of myogenin, a master gene of myogenic differentiation. We observed a prominent decrease in the nuclear binding activities of AP-1, Sp-1, and NF-kappa B already 12 to 24 …

Revendication. Chose fongible, Somme d'argent, Confusion avec d'autres fonds, Revendication (non), Demande tendant au paiement d'une somme d'argent, …

1998

International audience; (Com. 25 mars 1997, SA Editions Néressis c/ Sté France Télécom et autres ; CA Paris, 14 oct. 1997, Banque de Neuflize, Schlumberger, Mallet c/ Bertrand, ès qual.)

Gel chromatography

1968

Abstract The separation efficiency of gel chromatographic columns was investigated under a wide variety of experimental conditions. By use of reduced quantities it is possible to describe the separation efficiency for different gels and experimental conditions by a single equation. Deviations from this equation were found to be caused by an alteration of the diffusion coefficient within the gel with respect to the mobile phase. Factors governing the gel chromatography of p -oligophenylenes on poly(vinyl acetate) and poly(styrene) gels are generalized and discussed.

Evaluation of advanced silica packings for the separation of biopolymers by high-performance liquid chromatography

1987

Following previous studies of the use of non-porous monodisperse 1.5-microns n-octyl- and n-octadecyl-bonded silicas in gradient elution of proteins, this work was aimed at elucidating further the properties of this novel column material for peptide and protein separations in comparison with wide-pore silicas. First, it is demonstrated that with short columns (e.g., 35 X 8 mm I.D.) packed with these non-porous reversed-phase materials, mixtures of small peptides and mixtures of proteins can be very efficiently resolved. When the chain length of the bonded ligand was varied, the retention of a test set of proteins in gradient elution followed the ligand sequence C18 greater than C8 approxima…

Study of the effect of the membrane composition on ion transfer across a supported liquid membrane

2003

Abstract The rate of ion transfer across the supported liquid membrane (SLM) is studied in the rotating diffusion cell (RDC), varying the chemical composition of the SLM from net-cloth supported gel membranes to radiation-grafted polymer membranes. Steady-state current–voltage curves are measured as a function of the rotation rate, and values for the standard rate constant, k 0 , are determined for a series of tetraalkylammonium cations from the analysis of the initial slopes and the diffusion limiting currents. The analysis gives values for k 0 of the order of 10 −2 –10 −4 cm s −1 , which is in rather good agreement with the values found in the literature for this type of the system. As co…

Novel general expressions that describe the behavior of the height equivalent of a theoretical plate in chromatographic systems involving electricall…

2002

Novel general expressions are constructed and presented that describe the behavior of the height equivalent of a theoretical plate (plate height), H, as a function of the linear velocity, Vx, along the axis, x, of the column and the kinetic parameters that characterize the mass transfer and adsorption mechanisms in chromatographic columns. Open tube capillaries as well as columns packed with either non-porous or porous particles are studied. The porous particles could have unimodal or bimodal pore-size distributions and intraparticle convective fluid flow and pore diffusion are considered. The expressions for the plate height, H, presented in this work could be applicable to high-performanc…

1987