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Synthesis and Intracellular Transport of Mitochondrial Carbamyl Phosphate Synthetase I and Ornithine Transcarbamylase

  • Masataka Mori
  • Satoshi Miura
  • Tetsuo Morita
  • Masamiti Tatibana
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 153)

Abstract

Carbamyl phosphate synthetase I (CPS) and ornithine transcarbamylase (OTC), the first two enzymes of urea synthesis, are localized in the liver mitochondrial matrix of ureotelic animals.1 The two enzymes are coded by nuclear genes, synthesized on cytoplasmic 80 S ribosomes, and subsequently transported across the two mitochondrial membranes to the matrix space. Studies in our2,3 and other laboratories4,5 have shown that both enzymes are synthesized in larger precursor forms (pCPS and pOTC) in cell-free protein-synthesizing systems. These precursors form large aggregates and have conformations different from those of the mature enzymes.6 We further showed that pOTC was transported into isolated rat liver mitochondria in association with the processing of pOTC to the mature form of the enzyme.3,7,8 It has been shown that both pCPS9 and pOTC10 are synthesized on membrane-free polysomes, released into the cytosol and then transported rapidly into mitochondria. The present paper describes detailed kinetic studies of the synthesis, processing and intracellular transport of pCPS and pOTC in isolated rat hepatocytes. The paper also deals with the chemical nature of pOTC and its transport into isolated mitochondria in vi vitro.

Keywords

Intracellular Transport Flufenamic Acid Mature Enzyme Ornithine Transcarbamylase Putative Precursor 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Abbreviations

CPS

carbamyl phosphate synthetase I

pCPS

precursor of carbamyl phosphate synthetase I

OTC

ornithine transcarbamylase

pOTC

precursor of ornithine transcarbamylase

SDS

sodium dodecyl sulfate.

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Copyright information

© Springer Science+Business Media New York 1982

Authors and Affiliations

  • Masataka Mori
    • 1
  • Satoshi Miura
    • 1
  • Tetsuo Morita
    • 1
  • Masamiti Tatibana
    • 1
  1. 1.Department of BiochemistryChiba University School of MedicineInohana, Chiba 280Japan

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