Skip to main content

The smallest membrane anchoring subunit (QPs3) of bovine heart mitochondrial succinate-ubiquinone reductase. Cloning, sequencing, topology, and Q-binding domain.

Publication ,  Journal Article
Shenoy, SK; Yu, L; Yu, CA
Published in: J Biol Chem
July 11, 1997

The cDNA encoding the smallest membrane-anchoring subunit (QPs3) of bovine heart mitochondrial succinate-ubiquinone reductase was cloned and sequenced. This cDNA is 1330 base pairs long with an open reading frame of 474 base pairs that encodes the 103 amino acid residues of mature QPs3 and a 55-amino acid residue presequence. The cDNA insert has an 820-base pair long 3'-untranslated region, including a poly(A) tail. The molecular mass of QPs3, deduced from the nucleotide sequence, is 10,989 Da. QPs3 is a very hydrophobic protein; the hydropathy plot of the amino acid sequence reveals three transmembrane helices. Previous photoaffinity labeling studies of succinate-ubiquinone reductase, using 3-azido-2-methyl-5-methoxy[3H]-6-decyl-1,4-benzoquinone ([3H]azido-Q), identified QPs3 as one of the putative Q-binding proteins in this reductase. An azido-Q-linked peptide with a retention time of 66 min is obtained by high performance liquid chromatography of the chymotrypsin digest of carboxymethylated and succinylated [3H]azido-Q-labeled QPs3 purified from labeled succinate-ubiquinone reductase by a procedure involving phenyl-Sepharose 4B column chromatography, preparative SDS-polyacrylamide gel electrophoresis, and acetone precipitation. The amino acid sequence of this peptide is NH2-L-N-P-C-S-A-M-D-Y-COOH, corresponding to residues 29-37. The structure of QPs3 in the inner mitochondrial membrane is proposed based on the hydropathy profile of the amino acid sequence, on the predicted tendencies to form alpha-helices and beta-sheets, and on immunobinding of Fab' fragmenthorseradish peroxidase conjugates prepared from antibodies against two synthetic peptides, corresponding to the NH2 terminus region and the loop connecting helices 2 and 3 of QPs3, in mitoplasts and submitochondrial particles. The ubiquinone-binding domain in the proposed model of QPs3 is probably located at the end of transmembrane helix 1 toward the C-side of the mitochondrial inner membrane.

Duke Scholars

Altmetric Attention Stats
Dimensions Citation Stats

Published In

J Biol Chem

DOI

ISSN

0021-9258

Publication Date

July 11, 1997

Volume

272

Issue

28

Start / End Page

17867 / 17872

Location

United States

Related Subject Headings

  • Ubiquinone
  • Succinate Dehydrogenase
  • Software
  • Sequence Analysis, DNA
  • Protein Structure, Secondary
  • Protein Conformation
  • Polymerase Chain Reaction
  • Peptide Fragments
  • Oxidoreductases
  • Multienzyme Complexes
 

Citation

APA
Chicago
ICMJE
MLA
NLM

Published In

J Biol Chem

DOI

ISSN

0021-9258

Publication Date

July 11, 1997

Volume

272

Issue

28

Start / End Page

17867 / 17872

Location

United States

Related Subject Headings

  • Ubiquinone
  • Succinate Dehydrogenase
  • Software
  • Sequence Analysis, DNA
  • Protein Structure, Secondary
  • Protein Conformation
  • Polymerase Chain Reaction
  • Peptide Fragments
  • Oxidoreductases
  • Multienzyme Complexes