| Autor: |
Gouadon E; University of Ulm, Department of Applied Physiology, Albert-Einstein-Allee 11, D-89069 Ulm, Germany., Schuhmeier RP, Ursu D, Anderson AA, Treves S, Zorzato F, Lehmann-Horn F, Melzer W |
| Jazyk: |
angličtina |
| Zdroj: |
The Journal of physiology [J Physiol] 2006 Apr 01; Vol. 572 (Pt 1), pp. 269-80. Date of Electronic Publication: 2006 Jan 19. |
| DOI: |
10.1113/jphysiol.2005.104406 |
| Abstrakt: |
We investigated the functional role of JP-45, a recently discovered protein of the junctional face membrane (JFM) of skeletal muscle. For this purpose, we expressed JP-45 C-terminally tagged with the fluorescent protein DsRed2 by nuclear microinjection in myotubes derived from the C2C12 skeletal muscle cell line and performed whole-cell voltage-clamp experiments. We recorded in parallel cell membrane currents and Ca(2+) signals using fura-2 during step depolarization. It was found that properties of the voltage-activated Ca(2+) current were not significantly changed in JP-45-DsRed2-expressing C2C12 myotubes whereas the amplitude of depolarization-induced Ca(2+) transient was decreased compared to control myotubes expressing only DsRed2. Converting Ca(2+) transients to Ca(2+) input flux using a model fit approach to quantify Ca(2+) removal, the change could be attributed to an alteration in voltage-activated Ca(2+) permeability rather than to altered removal properties or a lower Ca(2+) content of the sarcoplasmic reticulum (SR). Determining non-linear capacitive currents revealed a reduction of Ca(2+) permeability per voltage-sensor charge. The results may be explained by a modulatory effect of JP-45 related to its reported in vitro interaction with the dihydropyridine receptor and the SR Ca(2+) binding protein calsequestrin (CSQ). |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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