INHIBITION BY CA2- RELATION TO THE CRABTREE EFFECT( OF THE HYDROLYSISAND THE SYNTHESIS OF ATP IN EHRLICH ASCITES TUMOR MITOCHONDRIA )

Citation
K. Bogucka et al., INHIBITION BY CA2- RELATION TO THE CRABTREE EFFECT( OF THE HYDROLYSISAND THE SYNTHESIS OF ATP IN EHRLICH ASCITES TUMOR MITOCHONDRIA ), Biochimica et biophysica acta. Bioenergetics, 1228(2-3), 1995, pp. 261-266
Citations number
54
Categorie Soggetti
Biology,Biophysics
ISSN journal
00052728
Volume
1228
Issue
2-3
Year of publication
1995
Pages
261 - 266
Database
ISI
SICI code
0005-2728(1995)1228:2-3<261:IBCRTT>2.0.ZU;2-2
Abstract
Phosphorylation of ADP and hydrolysis of ATP by isolated mitochondria from Ehrlich ascites tumour cells is greatly reduced when the mitochon dria have been preloaded with Ca2+ (50 nmol/mg protein or more). Trans location of ADP is diminished in Ca2+-loaded mitochondria. However, AT Pase in toluene-permeabilized mitochondria and in inside-out submitoch ondrial particles is also strongly inhibited by micromolar concentrati ons of Ca2+, indicating that, independently of adenine nucleotide tran sport, F1F0-ATPase is also affected. ATP hydrolysis by submitochondria l particles depleted of the inhibitory subunit of F1F0-ATPase (the Pul lman-Monroy protein inhibitor) is insensitive to Ca2+; however, this s ensitivity is restored when the particles are supplemented with the in hibitory subunit isolated from beef heart mitochondria. In view of the previous observations that glucose elicits in Ehrlich ascites tumour cells an increase of cytoplasmic free Ca2+ (Teplova, V.V., Bogucka, K. , Czyz, A., Evtodienko, Yu.V., Duszynski, J. and Wojtczak, L. (1993) B iochem. Biophys. Res. Commun. 196, 1148-1154) and that this calcium is then taken up by mitochondria, resulting in a strong inhibition of co upled respiration (Evtodienko, Yu.V., Teplova, V.V., Duszynski, J., Bo gucka, K. and Wojtczak, L. (1994) Cell Calcium 15, 439-446), the prese nt results are discussed in terms of the mechanism of the Crabtree eff ect in tumour cells.