Association of soluble matrix protein of Newcastle disease virus with liposomes is independent of ionic conditions.
An immunoaffinity method was designed for purification of a soluble form of the matrix (M) protein of Newcastle disease virus. The resulting M protein sedimented in a sucrose gradient as a small complex. This purified M protein associated with liposomes containing a net neutral, negative, or positive charge. The liposomes were composed of phosphatidylcholine, cholesterol, and a third lipid which provided the charge. The M protein-liposome associations were not prevented by high salt conditions. These observations are consistent with a nonelectrostatic association between the M protein and liposomes. Monoclonal antibodies to three separate epitopes of the M protein were all able to bind M protein complexed with liposomes, suggesting that the three M protein epitopes are not directly involved in the interaction between the M protein and liposomes. The M protein was also able to associate with liposomes lacking cholesterol implying that cholesterol does not play a substantial role in the M protein-liposome interaction.
Faaberg
K S
KS
Department of Immunology/Microbiology, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612.
Peeples
M E
ME
D000911:Antibodies, Monoclonal / Q000276:immunology; D000956:Antigens, Viral / Q000276:immunology; D011232:Chemical Precipitation; D002784:Cholesterol / Q000502:physiology; D007477:Ions; D008081:Liposomes; D008563:Membrane Lipids / Q000502:physiology; D009522:Newcastle disease virus / Q000648:ultrastructure*; D009994:Osmolar Concentration; D012995:Solubility; D014763:Viral Matrix Proteins / Q000276:immunology / Q000302:isolation & purification / Q000502:physiology*
D000911:Antibodies, Monoclonal; D000956:Antigens, Viral; D007477:Ions; D008081:Liposomes; D008563:Membrane Lipids; D014763:Viral Matrix Proteins; D002784:Cholesterol