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The effects of Ca2+ and GTP on the release of Ca2+ from the inositol 1,4,5-trisphosphate (IP3) sensitive Ca2+ compartment were investigated with digitonin permeabilized rat pancreatic acinar cells. The amount of Ca2+ released due to IP3 directly correlated with the amount of stored Ca2+ and was found to be inversely proportional to the medium free Ca2+ concentration. Ca2+ release induced by 0.18 microM IP3 was half maximally inhibited at 0.5 microM free Ca2+, i.e. at concentrations observed in the cytosol of pancreatic acinar cells. GTP did not cause Ca2+ release on its own, but a single addition of GTP (20 microM) abolished the apparent desensitization of the Ca2+ release which was observed during repeated IP3 applications. This effect of GTP was reversible. GTP gamma S could not replace GTP. Desensitization still occurred when GTP gamma S was added prior to GTP. The reported data indicate that GTP, stored Ca2+ and cytosolic free Ca2+ modulate the IP3 induced Ca2+ release.
R Engling, and
K J Föhr, and
T P Kemmer, and
M Gratzl
February 1990,
The Biochemical journal,
R Engling, and
K J Föhr, and
T P Kemmer, and
M Gratzl
February 1986,
Biochemical and biophysical research communications,
R Engling, and
K J Föhr, and
T P Kemmer, and
M Gratzl
June 1989,
The Journal of biological chemistry,
R Engling, and
K J Föhr, and
T P Kemmer, and
M Gratzl
April 1994,
The Journal of biological chemistry,
R Engling, and
K J Föhr, and
T P Kemmer, and
M Gratzl
January 1983,
Nature,
R Engling, and
K J Föhr, and
T P Kemmer, and
M Gratzl
February 1991,
Journal of neurochemistry,
R Engling, and
K J Föhr, and
T P Kemmer, and
M Gratzl
June 1998,
The Biochemical journal,
R Engling, and
K J Föhr, and
T P Kemmer, and
M Gratzl
October 1984,
The Biochemical journal,
R Engling, and
K J Föhr, and
T P Kemmer, and
M Gratzl
December 1987,
The Biochemical journal,
R Engling, and
K J Föhr, and
T P Kemmer, and
M Gratzl
May 1985,
The Biochemical journal,
