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Characterization and biosynthesis of cytochrome b(5) in rat liver microsomes

J R Sargent1, B P Vadlamudi

  • 1Department of Biological Chemistry, Marischal College, University of Aberdeen.

The Biochemical Journal
|May 1, 1968
PubMed

Insights

Cytochrome b(5) is released from rat liver microsomes by proteases and phospholipid disruptors. This protein is synthesized in rough microsomes and moves to smooth microsomes, incorporating amino acids into peptide linkage.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Background:

  • Rat liver microsomes contain cytochrome b(5) and cytochrome P-420.
  • Cytochrome b(5) can be released by proteolytic enzymes and phospholipid disruption.
  • Cytochrome P-420 is primarily released by phospholipid disruption.

Purpose of the Study:

  • To investigate the release mechanisms of cytochrome b(5) and cytochrome P-420 from rat liver microsomes.
  • To characterize the isolated cytochrome b(5) components.
  • To determine the site of cytochrome b(5) synthesis and its intracellular transport.

Main Methods:

  • Proteolytic enzyme treatment (trypsin) of rat liver microsomes.
  • Phospholipid disruption treatments.
  • Amino acid analysis and peptide mapping of isolated cytochrome b(5).
  • Radioactive amino acid incorporation studies in isolated rat liver microsomes.

Main Results:

  • Cytochrome b(5) and cytochrome P-420 exhibit differential release patterns.
  • Two distinct cytochrome b(5) components with identical spectral properties were isolated.
  • Cytochrome b(5) is synthesized in the rough microsomal fraction and subsequently found in the smooth fraction.
  • Isolated microsomes incorporate radioactive amino acids into cytochrome b(5) via peptide linkage.

Conclusions:

  • The release of cytochrome b(5) and P-420 is dependent on their interaction with microsomal membranes.
  • Cytochrome b(5) exists as at least two components, synthesized in rough microsomes and trafficked to smooth microsomes.

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