59 research outputs found
Biological Insights into the Expression of Translation Initiation Factors from Recombinant CHOK1SV Cell Lines and their Relationship to Enhanced Productivity
Translation initiation is on the critical pathway for the production of monoclonal antibodies (mAb) by mammalian cells. Formation of a closed loop structure comprised of mRNA, a number of eukaryotic initiation factors and ribosomal proteins has been proposed to aid re-initiation of translation and therefore increase global translational efficiency. We have determined mRNA and protein levels of the key components of the closed loop; eukaryotic initiation factors (eIF3a, eIF3b, eIF3c, eIF3h, eIF3i and eIF4G1), poly(A) binding protein (PABP) 1 and PABP interacting protein 1 (PAIP1) across a panel of 30 recombinant mAb-producing GS-CHOK1SV cell lines with a broad range of growth characteristics and production levels of a model recombinant mAb. We have used a multi-level statistical approach to investigate the relationship between key performance indicators (cell growth and recombinant antibody productivity) and the intracellular amounts of target translation initiation factor proteins and the mRNAs encoding them. We show that high-producing cell lines maintain amounts of the translation initiation factors involved in the formation of the closed loop mRNA, maintaining these proteins at appropriate levels to deliver enhanced recombinant protein production. We then utilise knowledge of the amounts of these factors to build predictive models for, and use cluster analysis to identify, high-producing cell lines. This study therefore defines the translation initiation factor amounts that are associated with highly productive recombinant GS-CHOK1SV cell lines that may be targets for screening highly productive cell lines or to engineer new host cell lines with the potential for enhanced recombinant antibody productivity
ÎłCOP Is Required for Apical Protein Secretion and Epithelial Morphogenesis in Drosophila melanogaster
Background: There is increasing evidence that tissue-specific modifications of basic cellular functions play an important role in development and disease. To identify the functions of COPI coatomer-mediated membrane trafficking in Drosophila development, we were aiming to create loss-of-function mutations in the ÎłCOP gene, which encodes a subunit of the COPI coatomer complex.
Principal Findings: We found that ÎłCOP is essential for the viability of the Drosophila embryo. In the absence of zygotic ÎłCOP activity, embryos die late in embryogenesis and display pronounced defects in morphogenesis of the embryonic epidermis and of tracheal tubes. The coordinated cell rearrangements and cell shape changes during tracheal tube morphogenesis critically depend on apical secretion of certain proteins. Investigation of tracheal morphogenesis in ÎłCOP loss-of-function mutants revealed that several key proteins required for tracheal morphogenesis are not properly secreted into the apical lumen. As a consequence, ÎłCOP mutants show defects in cell rearrangements during branch elongation, in tube dilation, as well as in tube fusion. We present genetic evidence that a specific subset of the tracheal defects in ÎłCOP mutants is due to the reduced secretion of the Zona Pellucida protein Piopio. Thus, we identified a critical target protein of COPI-dependent secretion in epithelial tube morphogenesis.
Conclusions/Significance: These studies highlight the role of COPI coatomer-mediated vesicle trafficking in both general and tissue-specific secretion in a multicellular organism. Although COPI coatomer is generally required for protein secretion, we show that the phenotypic effect of ÎłCOP mutations is surprisingly specific. Importantly, we attribute a distinct aspect of the ÎłCOP phenotype to the effect on a specific key target protein
Molecular recognition of a single sphingolipid species by a proteinâs transmembrane domain
Planetary Migration in Protoplanetary Disks
The known exoplanet population displays a great diversity of orbital architectures, and explaining the origin of this is a major challenge for planet formation theories. The gravitational interaction between young planets and their protoplanetary disks provides one way in which planetary orbits can be shaped during the formation epoch. Disk-planet interactions are strongly influenced by the structure and physical processes that drive the evolution of the protoplanetary disk. In this review we focus on how disk-planet interactions drive the migration of planets when different assumptions are made about the physics of angular momentum transport, and how it drives accretion flows in protoplanetary disk models. In particular, we consider migration in discs where: (i) accretion flows arise because turbulence diffusively transports angular momentum; (ii) laminar accretion flows are confined to thin, ionised layers near disk surfaces and are driven by the launching of magneto-centrifugal winds, with the midplane being completely inert; (iii) laminar accretion flows pervade the full column density of the disc, and are driven by a combination of large scale horizontal and vertical magnetic fields
A Conformational Change in the αâsubunit of Coatomer Induced by Ligand Binding to ÎłâCOP Revealed by Singleâpair FRET
Formation of transport vesicles involves polymerization of cytoplasmic coat proteins (COP). In COPI vesicle biogenesis, the heptameric complex coatomer is recruited to donor membranes by the interaction of multiple coatomer subunits with the budding machinery. Specific binding to the trunk domain of ÎłâCOP by the Golgi membrane protein p23 induces a conformational change that causes polymerization of the complex. Using singleâpair fluorescence resonance energy transfer, we find that this conformational change takes place in individual coatomer complexes, independent of each other, and that the conformational rearrangement induced in ÎłâCOP is transmitted within the complex to its αâsubunit. We suggest that capture of membrane protein machinery triggers cage formation in the COPI system
Le secteur privé, le secteur public et les médicaments essentiels génériques: le débat est ouvert.
info:eu-repo/semantics/publishe
Introducing contrast and luminance normalisation to improve the quality of subtractive resolution merge technique
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