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The effects of over-expressing an FKBP12.6 mutant that prevents calcineurin binding, on Ca sparks in permeabilised adult rabbit ventricular cardiomyocytes.
No full textThe effects of over-expressing an FKBP12.6 mutant that prevents calcineurin binding, on Ca sparks in permeabilised adult rabbit ventricular cardiomyocytes.
No full textFKBP12.6 overexpression alters the characteristics of SR Ca2+ release in permeabilized adult rabbit cardiac myocytes
No full textSorcin directly influences cardiac Na/Ca exchanger and ryanodine receptor activity via the sorcin C-terminal domain.
No full textOver-expression of FK506-binding protein 12.0,(FKBP12.0) alters excitation-contraction (EC) coupling in adult rabbit cardiomyocytes
No full textFKBP12.6 overexpression alters the characteristics of SR Ca2+ release in permeabilized adult rabbit cardiac myocytes
No full textThe W105G and W99G sorcin mutants demonstrate the role of the D helix in the Ca2+-dependent interaction with annexin VII and the cardiac ryanodine receptor
No full textSorcin, a 21.6 kDa two-domain penta-EF-hand (PEF) protein, when activated by Ca2+ binding, interacts with target proteins in a largely uncharacterized process. The two physiological EF-hands EF3 and EF2 do not belong to a structural pair but are connected by the D helix. To establish whether this helix is instrumental in sorcin activation, two D helix residues were mutated: W105, located near EF3 and involved in a network of interactions, and W99, located near EF2 and facing solvent, were substituted with glycine. Neither mutation alters calcium affinity. The interaction of the W105G and W99G mutants with annexin VII and the cardiac ryanodine receptor (RyR2), requiring the sorcin N- terminal and C-terminal domain, respectively, was studied. Surface plasmon resonance experiments show that binding of annexin VII to W99G occurs at the same Ca2+ concentration as that of the wild type, whereas W105G requires a significantly higher Ca2+ concentration. Ca2+ spark activity of isolated heart cells monitors the sorcin-RyR2 interaction and is unaltered by W105G but is reduced equally by W99G and the wild type. Thus, substitution of W105, via disruption of the network of D helix interactions, affects the capacity of sorcin to recognize and interact with either target at physiological Ca2+ concentrations, while mutation of solvent-facing W99 has little effect. The D helix appears to amplify the localized structural changes that occur at EF3 upon Ca2+ binding and thereby trigger a structural rearrangement that enables interaction of sorcin with its molecular targets. The same activation process may apply to other PEF proteins in view of the D helix conservation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
FKBP12 overexpression in isolated rabbit cardiomyocytes enhances intracellular Ca2+ transients, SIR Ca2+ content and contractility
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