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355 results on '"Fricke M"'

52. TCR-induced activation of Ras proceeds at the plasma membrane and requires palmitoylation of N-Ras

Author

RUBIO I, GRUND S, SONG SP, BISKUP C, BANDEMER S, FRICKE M, FÖRSTER M, A, WITTIG U, KLICHE S., GRAZIANI , ANDREA, Rubio, I, Grund, S, Song, Sp, Biskup, C, Bandemer, S, Fricke, M, Förster, M, Graziani, Andrea, A, Wittig, U, and Kliche, S.

Subjects
T cell, Lipoylation, Immunology, Receptors, Antigen, T-Cell, Biology, Oncogene Protein p21(ras), Endoplasmic Reticulum, Jurkat cells, Immunological synapse, Jurkat Cells, Palmitoylation, T-Lymphocyte Subsets, Anti-apoptotic Ras signalling cascade, Cell Line, Tumor, medicine, Immunology and Allergy, Animals, Guanine Nucleotide Exchange Factors, Humans, Fluorescent Dyes, T-cell receptor, Cell Membrane, Cell biology, Rats, DNA-Binding Proteins, Protein Transport, medicine.anatomical_structure, ras Proteins, ras Guanine Nucleotide Exchange Factors, Guanine nucleotide exchange factor, Protein Binding, Signal Transduction
Abstract

Ras transmits manifold signals from the TCR at various crossroads in the life of a T cell. For example, selection programs in the thymus or the acquisition of a state of hypo-responsiveness known as anergy are just some of the T cell features known to be controlled by TCR-sparked signals that are intracellularly propagated by Ras. These findings raise the question of how Ras can transmit such a variety of signals leading to the shaping of equally many T cell traits. Because Ras proteins transit through endomembrane compartments on their way to the plasma membrane (PM), compartmentalized Ras activation at distinct subcellular sites represents a potential mechanism for signal diversification in TCR signaling. This hypothesis has been nurtured by studies in T cells engineered to overexpress Ras that reported distinct activation of Ras at the PM and Golgi. Contrary to this scenario, we report in this study that activation of endogenous Ras, imaged in live Jurkat T cells using novel affinity probes for Ras-GTP, proceeds only at the PM even upon enforced signal flux through the diacylglycerol/RasGRP1 pathway. Physiological engagement of the TCR at the immunological synapse in primary T cells caused focalized Ras-GTP accumulation also only at the PM. Analysis of palmitoylation-deficient Ras mutants, which are confined to endomembranes, confirmed that the TCR does not activate Ras in that compartment and revealed a critical function for palmitoylation in N-Ras/H-Ras activation. These findings identify the PM as the only site of TCR-driven Ras activation and document that endomembranes are not a signaling platform for Ras in T cells.

Published
2010

61. Acidic peptides acting as growth modifiers of calcite crystals

Author

Volkmer, D, Fricke, M, Huber, T, and Sewald, Norbert

Subjects
Aspartic Acid, Phenylalanine, Microscopy, Electron, Scanning, Animals, Calcinosis, Proteins, ddc:530, Crystallization, Peptides, Calcium Carbonate
Abstract

Small acidic peptides comprising a repeating Phe-Asp sequence motif exert control, in vitro, on the morphology of calcite crystals similar to natural proteins from calcified tissues.

Published
2004

62. Interfacial electrostatics guiding the crystallization of CaCO3 underneath monolayers of calixarenes and resorcarenes

Author

Volkmer, D, Fricke, M, Agena, C, and Mattay, Jochen

Subjects
ddc:530
Abstract

The amphiphilic octaacids rccc-4,6,10,12,16,18,22,24-octakis-O-(carboxymethyl)-2,8,14,20-tetra(n-u ndecyl) resorc[4] arene (1) and 5,11,17,23,29,35,41,47-octakis(1,1,3,3-tetramethylbutyl)-49,50,51,52,53, 54,55,56-octa( carboxymethoxy) calix[8] arene (2) form stable monolayers at the air - water interface which induce growth of CaCO3 crystals at the monolayer-solution interface. Uniformly (012) oriented rhombohedral calcite single crystals grow underneath a monolayer of 2, whereas crystallization under a monolayer of 1 preferentially leads to formation of acicular aggregates of aragonite crystals. While polymorph selection and orientations of the CaCO3 crystals critically depend on the average charge density of the monolayer, the molecular shape and the particular Ca coordination behaviour of the amphiphiles that form the monolayer are of minor importance. CaCO3 crystal growth underneath monolayers of macrocyclic amphiphiles is briefly reviewed and the present experimental observations are compared to previous related investigations on "template-induced'' biomimetic mineralization.

Published
2004

66. Development of a systems theoretical procedure for evaluation of the work organization of the cockpit crew of a civil transport airplane

Author

Fricke, M and Vees, C

Subjects
Man/System Technology And Life Support
Abstract

To achieve optimum design for the man machine interface with aircraft, a description of the interaction and work organization of the cockpit crew is needed. The development of system procedure to evaluate the work organization of pilots while structuring the work process is examined. Statistical data are needed to simulate sequences of pilot actions on the computer. Investigations of computer simulation and applicability for evaluation of crew concepts are discussed.

Published
1983

71. Electronic structure of nanometer-size quantum dots and quantum rings

Author

Lorke, Axel, Luyken, Richard Johannes, Fricke, M., Kotthaus, Jörg P., Medeiros-Ribeiro, Gilberto, García Martínez, Jorge Manuel, Petroff, Pierre M., Lorke, Axel, Luyken, Richard Johannes, Fricke, M., Kotthaus, Jörg P., Medeiros-Ribeiro, Gilberto, García Martínez, Jorge Manuel, and Petroff, Pierre M.

Abstract

Recent experiments probing the conduction band electronic states in self-assembled dots, double dots and ring-like structures are reviewed. The results are discussed in view of contributions from quantization, magnetic forces and Coulomb interaction.

Published
1999

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