Ultrastructure of the membrane attack complex of complement: detection of the tetramolecular C9-polymerizing complex C5b-8.

Détails

ID Serval
serval:BIB_22034AA6FB37
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Ultrastructure of the membrane attack complex of complement: detection of the tetramolecular C9-polymerizing complex C5b-8.
Périodique
Proceedings of the National Academy of Sciences of the United States of America
Auteur⸱e⸱s
Tschopp J., Podack E.R., Müller-Eberhard H.J.
ISSN
0027-8424 (Print)
ISSN-L
0027-8424
Statut éditorial
Publié
Date de publication
1982
Volume
79
Numéro
23
Pages
7474-7478
Langue
anglais
Résumé
The ultrastructure of the membrane attack complex (MAC) of complement had been described as representing a hollow cylinder of defined dimensions that is composed of the proteins C5b, C6, C7, C8, and C9. After the characteristic cylindrical structure was identified as polymerized C9 [poly(C9)], the question arose as to the ultrastructural identity and topology of the C9-polymerizing complex C5b-8. An electron microscopic analysis of isolated MAC revealed an asymmetry of individual complexes with respect to their length. Whereas the length of one boundary (+/- SEM) was always 16 +/- 1 nm, the length of the other varied between 16 and 32 nm. In contrast, poly(C9), formed spontaneously from isolated C9, had a uniform tubule length (+/- SEM) of 16 +/- 1 nm. On examination of MAC-phospholipid vesicle complexes, an elongated structure was detected that was closely associated with the poly(C9) tubule and that extended 16-18 nm beyond the torus of the tubule and 28-30 nm above the membrane surface. The width of this structure varied depending on its two-dimensional projection in the electron microscope. By using biotinyl C5b-6 in the formation of the MAC and avidin-coated colloidal gold particles for the ultrastructural analysis, this heretofore unrecognized subunit of the MAC could be identified as the tetramolecular C5b-8 complex. Identification also was achieved by using anti-C5 Fab-coated colloidal gold particles. A similar elongated structure of 25 nm length (above the surface of the membrane) was observed on single C5b-8-vesicle complexes. It is concluded that the C5b-8 complex, which catalyzes poly(C9) formation, constitutes a structure of discrete morphology that remains as such identifiable in the fully assembled MAC, in which it is closely associated with the poly(C9) tubule.
Mots-clé
Complement C9, Complement Membrane Attack Complex, Complement System Proteins/physiology, Liposomes, Macromolecular Substances, Microscopy, Electron, Phosphatidylcholines, Structure-Activity Relationship
Pubmed
Web of science
Open Access
Oui
Création de la notice
24/01/2008 15:19
Dernière modification de la notice
20/08/2019 12:58
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