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Start Over Author "Nunez M" Journal journal of biological chemistry
5 results on '"Nunez M"'

1. Epidermal growth factor receptor binding is not a simple one-step process*

Author

Mayo, K H, Nunez, M, Burke, C, Starbuck, C, Lauffenburger, D, and Savage, C R

Abstract

The binding kinetics of 125I-labeled mouse epidermal growth factor (EGF) to receptors on human fibroblast cells in monolayer culture were measured at 4 ° C. Initial binding rates as a function of hormone concentration allowed estimation of simple two-state on-off rate constants of 1.2 × 106M−1s−1and 4.9 × 10−3s−1, respectively. These two-state parameters gave inadequate computer fits to long term kinetic and equilibrium-binding data, suggesting that an additional process(es) was occurring. Nonlinear equilibrium Scatchard plots and transient “pseudo-Scatchard” plots taken at pre-equilibrium times support the idea that at least one other process is occurring during receptor binding. 125I-EGF-receptor dissociation kinetic plots were biphasic, yielding rate constants of 1.5 × 10−2s−1and 5.6 × 10−5s−1with the ratio of the two components changing with the time of initial incubation with 125I-EGF. Application of a ternary complex model which assumed complexation of the bound receptor with a cell surface interaction molecule gave satisfactory fits to all data.

Published
1989
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3. Amines as inhibitors of iron transport in rabbit reticulocytes.

Author

Glass, J and Nunez, M T

Abstract

The effect of the known inhibitors of iron uptake, n-butylamine and NH4Cl, was examined at the molecular level to more precisely define the mechanisms by which these lysosomotropic agents block iron uptake by rabbit reticulocytes. Utilizing a rapid pulse-chase technique to follow the handling of a cohort of 59Fe, 125I-transferrin bound to rabbit reticulocytes, both amines were observed to have no effect on the cell-mediated release of 59Fe from internalized transferrin. The results indicated, however, that both agents acted to 1) retard the internalization of transferrin bound to transferrin receptors on the plasma membrane of reticulocytes, 2) retard the externalization of internalized transferrin, and 3) block the transport into the cytosol of iron released from transferrin.

Published
1986
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4. The Q-soluble N-Ethylmaleimide-sensitive Factor Attachment Protein Receptor (Q-SNARE) SNAP-47 Regulates Trafficking of Selected Vesicle-associated Membrane Proteins (VAMPs).

Author

Kuster A, Nola S, Dingli F, Vacca B, Gauchy C, Beaujouan JC, Nunez M, Moncion T, Loew D, Formstecher E, Galli T, and Proux-Gillardeaux V

Subjects
Animals, Dogs, Madin Darby Canine Kidney Cells, Protein Transport, Subcellular Fractions metabolism, Q-SNARE Proteins physiology, R-SNARE Proteins metabolism
Abstract

SNAREs constitute the core machinery of intracellular membrane fusion, but vesicular SNAREs localize to specific compartments via largely unknown mechanisms. Here, we identified an interaction between VAMP7 and SNAP-47 using a proteomics approach. We found that SNAP-47 mainly localized to cytoplasm, the endoplasmic reticulum (ER), and ERGIC and could also shuttle between the cytoplasm and the nucleus. SNAP-47 preferentially interacted with the trans-Golgi network VAMP4 and post-Golgi VAMP7 and -8. SNAP-47 also interacted with ER and Golgi syntaxin 5 and with syntaxin 1 in the absence of Munc18a, when syntaxin 1 is retained in the ER. A C-terminally truncated SNAP-47 was impaired in interaction with VAMPs and affected their subcellular distribution. SNAP-47 silencing further shifted the subcellular localization of VAMP4 from the Golgi apparatus to the ER. WT and mutant SNAP-47 overexpression impaired VAMP7 exocytic activity. We conclude that SNAP-47 plays a role in the proper localization and function of a subset of VAMPs likely via regulation of their transport through the early secretory pathway., (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)

Published
2015
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5. Delineation of the Xrcc4-interacting region in the globular head domain of cernunnos/XLF.

Author

Malivert L, Ropars V, Nunez M, Drevet P, Miron S, Faure G, Guerois R, Mornon JP, Revy P, Charbonnier JB, Callebaut I, and de Villartay JP

Subjects
Amino Acids, Binding Sites, Computer Simulation, Crystallography, X-Ray, DNA Repair, DNA Repair Enzymes chemistry, DNA Repair Enzymes genetics, DNA-Binding Proteins chemistry, DNA-Binding Proteins genetics, Humans, Mutagenesis, Site-Directed, Protein Binding, Protein Structure, Tertiary, DNA Repair Enzymes metabolism, DNA-Binding Proteins metabolism
Abstract

In mammals, the majority of DNA double-strand breaks are processed by the nonhomologous end-joining (NHEJ) pathway, composed of seven factors: Ku70, Ku80, DNA-PKcs, Artemis, Xrcc4 (X4), DNA-ligase IV (L4), and Cernunnos/XLF. Cernunnos is part of the ligation complex, constituted by X4 and L4. To improve our knowledge on the structure and function of Cernunnos, we performed a systematic mutagenesis study on positions selected from an analysis of the recent three-dimensional structures of this factor. Ten of 27 screened mutants were nonfunctional in several DNA repair assays. Outside amino acids critical for the expression and stability of Cernunnos, we identified three amino acids (Arg(64), Leu(65), and Leu(115)) essential for the interaction with X4 and the proper function of Cernunnos. Docking the crystal structures of the two factors further validated this probable interaction surface of Cernunnos with X4.

Published
2010
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