The cause of superstoichiometric CA2+ uptake and H+ ejection in L1210 mouse ascites tumor mitochondria

Baltazar Reynafarje, Albert L. Lehninger

Research output: Contribution to journalArticle


Mitochondria from L1210 mouse leukemia cells show superstoichiometric → H+/2e- ejection and → Ca2+/2e- uptake ratios in the absence of phosphate. Kinetic analysis of Ca2+-induced respiratory jumps shows a very rapid, early burst of H+ ejection and Ca2+ uptake dependent on energy-coupled electron transport but with extraordinarily high stoichiometry (→H+/2e- > 20; →Ca2+/2e- > 10), followed by a slower phase with normal stoichiometry (→H+/2e-=4-5; →Ca2+/2e-=4.0). The early burst of H+ ejection, which has a higher KM for Ca2+ than respiratory stimulation, accounts for the superstoichiometry phenomenon; it requires energization by state 4 respiration.

Original languageEnglish (US)
Pages (from-to)286-292
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number1
StatePublished - Mar 15 1974


ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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