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Rabbit skeletal sarcoplasmic reticulum vesicles were loaded with Ca2+ by ATP-dependent Ca2+ accumulation in the presence of low [Mg2+] (0.2-0.5 mM), and Ca2+ release was induced by addition of caffeine or ADP or by means of a Ca2+ jump. The levels of the phosphorylated intermediate (EP) and the tryptophan fluorescence of the Ca2+-ATPase were monitored during both the Ca2+ accumulation and the induced Ca2+ release using fast kinetic techniques. During Ca2+ uptake, both the EP level and the tryptophan fluorescence gradually decreased following a time course similar to that of the Ca2+ accumulation. Upon inducing Ca2+ release by addition of either caffeine or ADP, there was a transient increase of the EP level (from 0.3-0.5 to 1-2 nmol/mg protein) preceding the release of Ca2+. Similarly, a transient increase of the tryptophan fluorescence prior to Ca2+ release produced by the application of a Ca2+ jump was also found. These results indicate that the Ca2+-ATPase enzyme undergoes a rapid conformational change in response to triggering of Ca2+ release.
L G Mészáros, and
N Ikemoto
January 2001,
Membrane & cell biology,
L G Mészáros, and
N Ikemoto
January 1982,
Annals of the New York Academy of Sciences,
L G Mészáros, and
N Ikemoto
November 1983,
Biokhimiia (Moscow, Russia),
L G Mészáros, and
N Ikemoto
September 1986,
FEBS letters,
L G Mészáros, and
N Ikemoto
February 1995,
The Journal of biological chemistry,
L G Mészáros, and
N Ikemoto
January 1985,
The Journal of membrane biology,
L G Mészáros, and
N Ikemoto
February 1985,
Biochimica et biophysica acta,
L G Mészáros, and
N Ikemoto
January 1982,
Annals of the New York Academy of Sciences,
L G Mészáros, and
N Ikemoto
February 1982,
Molecular and cellular biochemistry,
L G Mészáros, and
N Ikemoto
March 1982,
FEBS letters,
