Function and membrane topology of wild-type and mutated cytochrome P-450c21

Meng Chun Hu, Li Chung Hsu, Nai Chi Hsu, Bon Chu Chung

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

We have studied membrane topology of cytochrome P-450c21 (P450c21) using the approaches of mutagenesis and protease digestion. P450c21 is located at the cytoplasm with an N-terminal hydrophobic domain integrated into microsomal membranes. When this hydrophobic domain was replaced by a secretory signal peptide, P450c21 was translocated into the lumen and lost enzymic activity. No other topogenic sequence was detected in the bulk of the P450c21 peptide. A mutant protein with Pro-30 replaced by Leu (L30) corresponding to the mutation found in the diseased state was created. L30 protein lost 90% of enzymic activity, while a double mutant (L30R32) with an additional Leu-32 to Arg mutation had slightly higher residual enzymic activity. Apart from lower activity, L30 was also present in the cell at a lower level than wild-type P450c21. This lower level is probably due to increased degradation, as L30 is synthesized at a normal rate. Both L30 and L30R32 proteins, however, were integrated into membranes normally. Therefore the Pro-30 → Leu mutation did not affect membrane integration, but affected the abundance and enzymic activity of P450c21.

Original languageEnglish
Pages (from-to)325-329
Number of pages5
JournalBiochemical Journal
Volume316
Issue number1
DOIs
Publication statusPublished - May 15 1996

Fingerprint

L 30
Cytochromes
Topology
Membranes
Mutation
Mutagenesis
Mutant Proteins
Protein Sorting Signals
Proteins
Peptide Hydrolases
Digestion
Cytoplasm
Degradation

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Function and membrane topology of wild-type and mutated cytochrome P-450c21. / Hu, Meng Chun; Hsu, Li Chung; Hsu, Nai Chi; Chung, Bon Chu.

In: Biochemical Journal, Vol. 316, No. 1, 15.05.1996, p. 325-329.

Research output: Contribution to journalArticle

Hu, Meng Chun ; Hsu, Li Chung ; Hsu, Nai Chi ; Chung, Bon Chu. / Function and membrane topology of wild-type and mutated cytochrome P-450c21. In: Biochemical Journal. 1996 ; Vol. 316, No. 1. pp. 325-329.
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