Proteolysis of mitochondria in reticulocytes during maturation is ubiquitin‐dependent and is accompanied by a high rate of ATP hydrolysis

Abstract

The ATP-dependent breakdown of mitochondria-containing stroma proceeds via the ubiquitin-requiring pathway. The proteolysis is linked to a large ATP-cleaved consumption amounting to 1 ATP per peptide bond or more. Proteins of mitochondria-containing stroma are much better substrates of ATP-ubiquitindependent proteolysis than heat-denatured ones. Hemin suppresses both proteolysis and ATP hydrolysis.

Conjugation of Ubiquitin to Proteins from Green Plant Tissues

“…Although considerable conjugation occurs at lower pH values, these high pH values are found only in the stroma in the chloroplasts and the mitochondria matrix. Ubiquitin-dependent proteolysis has been described in reticulocyte mitochondria (21), and our results show not only that RuBPCase can undergo ubiquitin-dependent degradation in vitro (Fig. 4), but also the existence ofthe conjugating enzymes in chloroplasts (Figs.…”

Regulation of mitochondrial proteolysis

“…This effect was equally observed in the case of degradation by the lysosomal extract (as shown) and also with a reticulocyte extract (not shown) which we have tested for comparative purposes, since it contains a very active ATPdependent proteolytic system directed to the destruction of mitochondria during cell maturation [12].…”

Energy metabolism reactions in ruminant muscle: responses to age, nutrition and hormonal status

“…In reticulocytes the inhibition of intracellular proteolysis effected a saving equivalent to 1 ATP per peptide bond hydrolysed (Siems et al, 1984;Rapoport et al, 1985). Recently Driscoll and Goldberg (1989) demonstrated that the proteasome (a multicatalytic endoproteinase complex) is activated 4-12-fold by ATP.…”