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Silverstein N.,Hebrew University of Jerusalem | Ewers D.,Jülich Research Center | Ewers D.,Institute For Neurophysiology | Forrest L.R.,U.S. National Institutes of Health | And 2 more authors.
Journal of Biological Chemistry | Year: 2015

Background: Archaeal and brain transporters differ in substrate specificity. Results: Two residues from hairpin 2 play a role in the substrate specificity of a glutamate transporter homologue. Conclusion: Hairpin 2 plays a role in the selection and translocation of the substrate. Significance: This work provides new insights into the molecular basis of substrate specificity of transporters.

Braunewell K.-H.,Institute for Neurophysiology | Braunewell K.-H.,Southern Research Institute | Paul B.,Griffith University | Altarche-Xifro W.,Institute for Neurophysiology | And 3 more authors.
Australian Journal of Chemistry | Year: 2010

The subcellular membrane localization of neuronal calcium sensor (NCS) proteins in living cells, such as Visinin-like Proteins-1 (VILIP-1) and VILIP-3, differs substantially. We have followed the hypothesis that the differential localization may be due to the specific binding capabilities of individual VILIPs for phosphatidylinositol phosphates (PIPs). Several highly conserved lysine residues in the N-terminal region could provide favourable electrostatic interactions. Molecular modelling results support a binding site for phospho-inositides in the N-terminal area of VILIP-1, and the involvement of the conserved N-terminal lysine residues in binding the phospho-inositol head group. Experimentally, the binding of VILIP-1 to inositol derivatives was tested by a PIP strip assay, which showed the requirement of phosphorylation of the inositol group for the interaction of the protein with PIPs. Monolayer adsorption measurements showed a preference of VILIP-1 binding to PI(4,5)P 2 over PI(3,4,5)P3. The co-localization of VILIP-1 with PI(4,5)P2 at the cell surface membrane in hippocampal neurons further supports the idea of direct interactions of VILIP-1 with PIPs in living cells. © 2010 CSIRO.

Treskes P.,University of Cologne | Treskes P.,Heart Center | Treskes P.,Institute for Neurophysiology | Neef K.,University of Cologne | And 16 more authors.
Journal of Thoracic and Cardiovascular Surgery | Year: 2015

Objective: Skeletal myoblasts fuse to form functional syncytial myotubes as an integral part of the skeletal muscle. During this differentiation process, expression of proteins for mechanical and electrical integration is seized, which is a major drawback for the application of skeletal myoblasts in cardiac regenerative cell therapy, because global heart function depends on intercellular communication. Methods: Mechanically preconditioned engineered tissue constructs containing neonatal mouse skeletal myoblasts were transplanted epicardially. A Y-chromosomal specific polymerase chain reaction (PCR) was undertaken up to 10 weeks after transplantation to confirm the presence of grafted cells. Histologic and electrophysiologic analyses were carried out 1 week after transplantation. Results: Cells within the grafted construct expressed connexin 43 at the interface to the host myocardium, indicating electrical coupling, confirmed by sharp electrode recordings. Analyses of the maximum stimulation frequency (5.65 ± 0.37 Hz), conduction velocity (0.087 ± 0.011 m/s) and sensitivity for pharmacologic conduction block (0.736 ± 0.080 mM 1-heptanol) revealed effective electrophysiologic coupling between graft and host cells, although significantly less robust than in native myocardial tissue (maximum stimulation frequency, 11.616 ± 0.238 Hz, P<.001; conduction velocity, 0.300 ± 0.057 m/s, P<.01; conduction block, 1.983 ± 0.077 mM 1-heptanol, P<.001). Conclusions: Although untreated skeletal myoblasts cannot couple to cardiomyocytes, we confirm that mechanical preconditioning enables transplanted skeletal myoblasts to functionally interact with cardiomyocytes in vivo and, thus, reinvigorate the concept of skeletal myoblast-based cardiac cell therapy. Copyright © 2015 by The American Association for Thoracic Surgery.

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