Topological organization of subunits VII and VIII in the ubiquinolcytochrome c oxidoreductase of Saccharomyces cerevisiae

FEBS Letters

Grivell, Leslie A.¹  Berden, Jan A.²  Boumans, Hans² 

[1] Section for Molecular Biology, Department of Molecular Cell Biology, University of Amsterdam, Amsterdam, The Netherlands;E.C. Slater Institute, University of Amsterdam, Plantage Muidergracht 12, 1018 TV Amsterdam, The Netherlands

关键词: Membrane topology;    Ubiquinol-cytochrome c oxidoreductase;    Epitope tagging;    Integral membrane protein;    (Saccharomyces cerevisiae);   

DOI  :  10.1016/0014-5793(96)00642-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

To determine the topology of subunit VIII of the yeast ubiquinol-cytochrome c oxidoreductase in the mitochondrial inner membrane, an epitope has been introduced in the N-terminal half of this protein. Previous topology studies had shown that at least the C-terminus faces the intermembrane space [Hemrika and Berden (1990) Eur. J. Biochem. 192, 761–765]. Based on sensitivity of the protein to proteinase K digestion we now suggest that the N-terminus of subunit VIII is similarly oriented, implying that this subunit does not span the membrane. Despite this, however, subunit VIII cannot be extracted from the membrane even after treatment with 0.1 M Na₂CO₃ at pH 11.5, showing that the protein is integrally embedded in the membrane. A similar behaviour was displayed by another low molecular weight protein of the complex, subunit VII, which faces the matrix side. A model for the topology of these subunits in the membrane is discussed with respect to the structure of the complex and their involvement in quinone binding.

【 授权许可】

Unknown