scholarly journals The role of mitochondria in modifying calcium-sensitive cytoplasmic metabolic activities. Modification of pyruvate kinase activity

1972 ◽  
Vol 128 (2) ◽  
pp. 415-420 ◽  
Author(s):  
J. Meli ◽  
F. L. Bygrave
Keyword(s):  
Pyruvate Kinase ◽  
Rat Liver ◽  
Kinase Activity ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Pyruvate Kinase Activity ◽  
Metabolic Activities ◽  
The One

1. The modification of pyruvate kinase activity in vitro was examined by altering the environmental [Mg2+]/[Ca2+] ratio with EDTA on the one hand and isolated rat liver mitochondria on the other. 2. Controlled additions of Ca2+ and EDTA caused pyruvate kinase activity to be alternately and rapidly switched on and off. 3. By being able to accumulate Ca2+ in preference to Mg2+ rat liver mitochondria were able to alter the [Mg2+]/[Ca2+] ratio in the vicinity of pyruvate kinase and thereby modify the activity of this enzyme. 4. The possible role of mitochondria in modifying pyruvate kinase and other ion-sensitive cytoplasmic enzyme activities is discussed.

scholarly journals Role of polyamines in the transport in vitro of the precursor of ornithine transcarbamylase

1991 ◽  
Vol 279 (3) ◽  
pp. 815-820 ◽  
Author(s):  
C González-Bosch ◽  
M J Marcote ◽  
J Hernández-Yago
Keyword(s):  
Rat Liver ◽  
Signal Sequence ◽  
Chimeric Protein ◽  
Liver Mitochondria ◽  
Ornithine Transcarbamylase ◽  
Rat Liver Mitochondria ◽  
Surface Transport ◽  
Binding To Mitochondria

Polyamines induce the transport in vitro of the rat liver precursor of ornithine transcarbamylase (pOTC) into isolated rat liver mitochondria. The accumulation of this precursor at the level of binding to the mitochondrial surface has allowed us to establish that polyamines are involved in the interaction of the precursor with the mitochondrial surface. Transport of a chimeric protein having the signal sequence of pOTC fused to a fragment of the cytosolic protein human arginosuccinate lyase was also induced by polyamines. The sensitivity of the pOTC synthesized in vitro and of the chimeric protein to proteinases decreases in the presence of polyamines. This result suggests that polyamines may play a role in modulating the folding of precursors to favour their binding to mitochondria.

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