Glutathione-catalyzed disulfide-linking of C9 in the membrane attack complex of complement

K. Yamamoto, T. Kawashima, S. Migita

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The membrane attack complex of complement (the dimeric C5b-9 complex) is a multimolecular assemblage of five proteins (C5b, C6, C7, C8, and C9) which are held together by noncovalent forces. We found that C9 molecules in the complex can be covalently cross-linked (disulfide-linked) by glutathione. In this experiment, the tetramolecular C5b-8 complex bound to phospholipid vesicles was first prepared from purified C5b-6, C7, and C8. The vesicle-bound C5b-8 complex was then incubated (37°C, 20 min) with an excess of 131I-C9 in the presence of 1 mM glutathione; an average of 5.3 molecules of C9 per C5b-8 were bound and the C5b-9 complex formed was predominantly a dimeric C5b-9 complex. About one-third of C9 in this C5b-9 complex was found to be in a disulfide-linked dimeric form. The C5b-9 complex, having only a average of 0.9 molecules of C9 per C5b-8, was also prepared in the presence of glutathione; this C5b-9 preparation contained both monomeric and dimeric C5b-9 complexes, and about one-fifth of the C9 subunits was in a cross-linked dimeric form. By contrast, C9 in the absence of the C5b-8 complex was not significantly cross-linked by glutathione. These results indicate that C9 has a unique property to associate with itself upon reaction with the C5b-8 complex.

Original languageEnglish
Pages (from-to)8573-8576
Number of pages4
JournalJournal of Biological Chemistry
Volume257
Issue number15
Publication statusPublished - Dec 1 1982
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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