Open AccessVisualization of specific antibody and C1q binding to hapten-sensitized lipid vesicles.
Author(s) -
Nelly Henry,
J W Parce,
H. M. McConnell
Publication year - 1978
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.75.8.3933
Subject(s) - hapten , chemistry , vesicle , spin label , biophysics , antibody , immunoglobulin g , lipid bilayer , membrane , biochemistry , biology , immunology
Specific IgG antibodies directed against the spin-label nitroxide group present as a lipid hapten in single-compartment lipid vesicles have been visualized by using freeze-etch electron microscopy. Individual "particles" with diameters of the order of 20 nm are identified as single IgG molecules bound to lipid hapten. No significant aggregation of these IgG molecules was observed over a period of 1 hr in a dipalmitoyl phosphatidylcholine vesicle at 22 degrees. Binding of the human complement component C1q results in the formation of large (approximately 50-100 nm) asymmetric particles having a partially resolved substructure that may arise from individual IgG molecules bound to the membranes as well as to C1q. The binding of C1q appears to result in a clustering of membrane-bound IgG molecules. Samples containing a serum factor (perhaps anti-IgG antibodies) exhibit some IgG clustering distinct from that produced by Clq.