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  • The EMBO Journal (2000) 19, 4493 - 4502
  • doi:10.1093/emboj/19.17.4493

The CXXCXXC motif determines the folding, structure and stability of human Ero1-Lalpha

A.M. Benham1, A. Cabibbo2, A. Fassio2, N. Bulleid3, R. Sitia2 and I. Braakman1

  1. Department of Biochemistry, Academic Medical Center, Meibergdreef 15, 1105 AZ Amsterdam and Department of Bio-Organic Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
  2. Molecular Immunology Unit, DIBIT-HSR, Via Olgettina 58, 20132 Milan, Italy
  3. School of Biological Sciences, University of Manchester, 2.205 Stopford Building, Manchester, UK

Correspondence to:

I. Braakman, E-mail: I.Braakman@chem.uu.nl

Received 27 May 2000; Accepted 12 July 2000; Revised 12 July 2000

The presence of correctly formed disulfide bonds is crucial to the structure and function of proteins that are synthesized in the endoplasmic reticulum (ER). Disulfide bond formation occurs in the ER owing to the presence of several specialized catalysts and a suitable redox potential. Work in yeast has indicated that the ER resident glycoprotein Ero1p provides oxidizing equivalents to newly synthesized proteins via protein disulfide isomerase (PDI). Here we show that Ero1-Lalpha, the human homolog of Ero1p, exists as a collection of oxidized and reduced forms and covalently binds PDI. We analyzed Ero1-Lalpha cysteine mutants in the presumed active site C391VGCFKC397. Our results demonstrate that this motif is important for protein folding, structural integrity, protein half-life and the stability of the Ero1-Lalpha–PDI complex.

  • Keywords:

    • chaperones,
    • disulfide bonds,
    • endoplasmic reticulum,
    • protein folding,
    • redox