Abstract
The Ca2+ ionophore X-537A is employed as a tool to distinguish between intravesicular Ca2+ and surface membrane-bound Ca2+ in sarcoplasmic reticulum isolated from rabbit skeletal muscle. When sarcoplasmic reticulum is incubated in 20 mM Ca2+ in the absence of ATP, 10-12 h are necessary for measurable amount of Ca2+ to penetrate into the vesicular space, as determined by the fact that X-537A releases Ca2+ from 'loaded' vesicles only after this period of incubation. A fraction of Ca2+ of 50-60 nmol/mg protein, rapidly taken up by sarcoplasmic reticulum, exchanges with Mg2+ and K+ in the medium and is readily released by ethyleneglycol-bis-(beta-aminoethyl ether)-N,N'-tetraacetic acid, but it is not released by X-537A. The slow-penetrating fraction of Ca2+ (30-40 nmol/mg protein) is rapidly released X-537A. The results indicate that most of the Ca2+ retained by sarcoplasmic reticulum under conditions of passive uptake is bound to the external side of the membrane. The fraction of Ca2+ that slowly penetrates the vesicles remains essentially free inside the vesicles and only a small part is bound to the internal side of the membrane.
References
Dec 17, 1973·European Journal of Biochemistry·D A Thorley-Lawson, N M Green
Aug 1, 1970·The Journal of General Physiology·P F Duggan, A Martonosi
Oct 1, 1970·Journal of Biochemistry·T KanazawaY Tonomura
Jun 1, 1972·Journal of Bioenergetics·R J Baskin
Dec 1, 1972·The Journal of General Physiology·A ScarpaG Inesi
Dec 1, 1972·Journal of Biochemistry·S YamadaY Tonomura
Oct 19, 1973·Biochimica Et Biophysica Acta·M G Vale, A P Carvalho
Dec 25, 1973·Journal of Molecular Biology·G InesiS Eletr
Feb 18, 1974·Annals of the New York Academy of Sciences·D H MacLennanP S Stewart
Sep 1, 1972·Journal of Biochemistry·H NakamuraT Mitsui
Sep 1, 1974·Archives of Biochemistry and Biophysics·D C PangR S Rogowski
Nov 1, 1972·Archives of Biochemistry and Biophysics·D W Deamer, R J Baskin
Nov 6, 1973·Biochemistry·H Masuda, L de Meis
May 7, 1974·Biochemistry·L de Meis, H Masuda
Jan 17, 1972·Biochimica Et Biophysica Acta·R Panet, Z Selinger
Feb 1, 1966·Journal of Cellular Physiology·A P Carvalho
May 1, 1967·The Journal of General Physiology·A P Carvalho, B Leo
Jan 30, 1971·FEBS Letters·B BarlogieM Makinose
Jan 30, 1971·FEBS Letters·M Makinose
Jan 30, 1971·FEBS Letters·M Makinose, W Hasselbach
Sep 1, 1972·FEBS Letters·M Makinose
Apr 3, 1962·Biochemical and Biophysical Research Communications·W HASSELBACH, M MAKINOSE
Sep 1, 1962·The Journal of Cell Biology·S Ebashi, F Lipmann
Citations
Jan 1, 1979·General Pharmacology·S J Sulakhe, P V Sulakhe
May 1, 1985·Journal of Neurosurgery·K J BarryV Gavris
May 1, 1977·Archives of Biochemistry and Biophysics·N Krasnow
Oct 1, 1980·Archives of Biochemistry and Biophysics·M G Vale
Aug 1, 1983·Archives of Biochemistry and Biophysics·E OkabeH Ito
Apr 22, 1981·Biochimica Et Biophysica Acta·M G Vale, A P Carvalho
Dec 15, 1985·Biochemical Pharmacology·M G Vale
Jun 1, 1990·Archives of Biochemistry and Biophysics·M G Vale
Jan 1, 1977·Pflügers Archiv : European journal of physiology·C BehnP Weskamp
Aug 11, 1982·Biochimica Et Biophysica Acta·M C Berman
Nov 15, 1977·Biochimica Et Biophysica Acta·M G Vale
Oct 2, 1980·Biochimica Et Biophysica Acta·M G Vale, A P Carvalho
May 2, 1977·Biochimica Et Biophysica Acta·R Käser-GlanzmannE F Lüscher