Phosphoenolpyruvate partially inhibits the accumulation of Ca(2+) in isolated mung bean (Phaseolus aureus Roxb.) mitochondria. Succinate-supported Ca(2+) uptake is twice as sensitive to phosphoenolpyruvate inhibition as is NADH- or malate/pyruvate-supported Ca(2+) uptake. Pyruvate, atractylate, and ATP, but not ITP, reverse the phosphoenolpyruvate-induced inhibition. Oxaloacetic acid inhibits succinate-supported Ca(2+) uptake completely while partially inhibiting NADH-supported Ca(2+) uptake. The oxaloacetate inhibition of NADH-supported Ca(2+) uptake is greater than that produced by phosphoenolpyruvate. It is suggested that inhibition of Ca(2+) uptake is due to the conversion of phosphoenolpyruvate into oxaloacetate via phosphoenolpyruvate carboxykinase, with oxaloacetate responsible for the actual inhibition of Ca(2+) uptake.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
