scholarly journals A structure-effect study of the induction by polyamines of the transport in vitro of the precursor of ornithine transcarbamylase

1994 ◽  
Vol 300 (1) ◽  
pp. 277-280 ◽  
Author(s):  
M J Marcote ◽  
D Corella ◽  
C González-Bosch ◽  
J Hernández-Yago
Keyword(s):  
Marked Decrease ◽  
Liver Mitochondria ◽  
Effect Study ◽  
Ornithine Transcarbamylase ◽  
Rat Liver Mitochondria ◽  
Amino Groups ◽  
Isolated Rat Liver ◽  
Related Compounds ◽  
Polyamine Derivatives

Polyamines induce the transport in vitro of the precursor of ornithine transcarbamylase (pOTC) into isolated rat liver mitochondria by facilitating its functional binding to these organelles. Comparative studies of the effect on the in vitro transport of pOTC of polyamine derivatives and related compounds have allowed us to establish that: (i) at least two protonated amino groups per molecule are necessary to induce the pOTC transport; (ii) a distance of three -CH2- groups between the amino groups in diamines is enough to induce this effect, although no differences were observed with diamines having distances of three to eight -CH2- groups. Longer distances resulted in a marked decrease of the effect.

scholarly journals Protein-mediated uptake of vitamin B12 by isolated mitochondria

Blood ◽  
1976 ◽  
Vol 47 (6) ◽  
pp. 923-930 ◽  
Author(s):  
RA Gams ◽  
EM Ryel ◽  
F Ostroy
Keyword(s):  
Vitamin B12 ◽  
Rat Liver ◽  
Mitochondrial Respiration ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Isolated Rat Liver ◽  
Isolated Mitochondria ◽  
Isolated Rat

Abstract Protein-mediated B12 uptake by isolated rat liver mitochondria has been shown to be enhanced by plasma transcobalamin (TC-II) but not by salivary R binder in vitro. The process is enhanced by calcium and depends on active mitochondrial respiration. Following uptake, cyanocobalamin is converted to adenosyl and methylcobalamins and released from the mitochondria. TC-II appears to be required for both cellular and mitochondrial uptake of vitamin B12.

scholarly journals Protein-mediated uptake of vitamin B12 by isolated mitochondria

Blood ◽  
1976 ◽  
Vol 47 (6) ◽  
pp. 923-930
Author(s):  
RA Gams ◽  
EM Ryel ◽  
F Ostroy
Keyword(s):  
Vitamin B12 ◽  
Rat Liver ◽  
Mitochondrial Respiration ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Isolated Rat Liver ◽  
Isolated Mitochondria ◽  
Isolated Rat

Protein-mediated B12 uptake by isolated rat liver mitochondria has been shown to be enhanced by plasma transcobalamin (TC-II) but not by salivary R binder in vitro. The process is enhanced by calcium and depends on active mitochondrial respiration. Following uptake, cyanocobalamin is converted to adenosyl and methylcobalamins and released from the mitochondria. TC-II appears to be required for both cellular and mitochondrial uptake of vitamin B12.

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.

scholarly journals Import of rat ornithine transcarbamylase precursor into mitochondria: two-step processing of the leader peptide.

1987 ◽  
Vol 105 (6) ◽  
pp. 2631-2639 ◽  
Author(s):  
E S Sztul ◽  
J P Hendrick ◽  
J P Kraus ◽  
D Wall ◽  
F Kalousek ◽  
...  
Keyword(s):  
Amino Acids ◽  
Cleavage Site ◽  
Liver Mitochondria ◽  
Essential Elements ◽  
Ornithine Transcarbamylase ◽  
Proteolytic Processing ◽  
Leader Peptide ◽  
Rat Liver Mitochondria

The mitochondrial matrix enzyme ornithine transcarbamylase (OTC) is synthesized on cytoplasmic polyribosomes as a precursor (pOTC) with an NH2-terminal extension of 32 amino acids. We report here that rat pOTC synthesized in vitro is internalized and cleaved by isolated rat liver mitochondria in two, temporally separate steps. In the first step, which is dependent upon an intact mitochondrial membrane potential, pOTC is translocated into mitochondria and cleaved by a matrix protease to a product designated iOTC, intermediate in size between pOTC and mature OTC. This product is in a trypsin-protected mitochondrial location. The same intermediate-sized OTC is produced in vivo in frog oocytes injected with in vitro-synthesized pOTC. The proteolytic processing of pOTC to iOTC involves the removal of 24 amino acids from the NH2 terminus of the precursor and utilizes a cleavage site two residues away from a critical arginine residue at position 23. In a second cleavage step, also catalyzed by a matrix protease, iOTC is converted to mature OTC by removal of the remaining eight residues of leader sequence. To define the critical regions in the OTC leader peptide required for these events, we have synthesized OTC precursors with alterations in the leader. Substitution of either an acidic (aspartate) or a "helix-breaking" (glycine) amino acid residue for arginine 23 of the leader inhibits formation of both iOTC and OTC, without affecting translocation. These mutant precursors are cleaved at an otherwise cryptic cleavage site between residues 16 and 17 of the leader. Interestingly, this cleavage occurs at a site two residues away from an arginine at position 15. The data indicate that conversion of pOTC to mature OTC proceeds via the formation of a third discrete species: an intermediate-sized OTC. The data suggest further that, in the rat pOTC leader, the essential elements required for translocation differ from those necessary for correct cleavage to either iOTC or mature OTC.

Respiratory activity of isolated rat liver mitochondria following in vitro exposure to oxygen species: A threshold study

1990 ◽  
Vol 51 (3) ◽  
pp. 249-263 ◽  
Author(s):  
Philippe Corbisier ◽  
Martine Raes ◽  
Carine Michiels ◽  
Etienne Pigelolet ◽  
Andree Houbion ◽  
...  
Keyword(s):  
Rat Liver ◽  
Respiratory Activity ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Oxygen Species ◽  
Isolated Rat Liver ◽  
In Vitro Exposure ◽  
Isolated Rat
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