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Incorporation of P 0 Protein into Liposomes: Demonstration of a Two‐Domain Structure by Immunochemical and PAGE Analysis
Author(s) -
Koski Carol L.,
Franko Maryellen C.,
Hudson C. Sue,
Shin Mopn L.
Publication year - 1984
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1984.tb02759.x
Subject(s) - liposome , myelin , chemistry , monoclonal antibody , trypsin , biochemistry , phosphatidylcholine , phosphatidylethanolamine , bilayer , antiserum , microbiology and biotechnology , antibody , biology , phospholipid , immunology , membrane , enzyme , central nervous system , neuroscience
The amphiphilic nature of P 0 , the major glycoprotein of peripheral nerve myelin, has been suggested previously. In the present study, purified P 0 from human peripheral nerve myelin was incorporated into an artificial lipid bilayer consisting of dimyristoyl lecithin and cholesterol. The liposomes were fractionated on a sucrose gradient. The continued expression of P 0 antigenicity by the liposomes was shown by specific complement consumption with a multivalent antiserum against P 0 or with an IgM monoclonal antibody. Both antibodies recognized P 0 expressed on the surface of peripheral nerve myelin and the P 0 liposomes. P 0 liposomes and peripheral nerve myelin treated with trypsin lost the surface determinant that reacted with the monoclonal antibody. Analysis of the trypsin‐treated liposomes and peripheral nerve myelin by polyacrylamide gel electrophoresis revealed molecular weights for this protein of 19,500 and 20,500, respectively. Similar treatment of the P 0 in the fluid phase resulted in many smaller fragments. These results indicate that P 0 consists of two domains, a hydrophilic domain accessible to trypsin digestion and a hydrophobic domain, which is potentially trypsin‐sensitive, but shielded by the lipid bilayer. Binding studies with an anti‐P 0 monoclonal antibody and polyacrylamide gel analysis of the lipid‐shielded P 0 fragment in liposomes and peripheral nerve myelin suggest that the orientation of the protein in the liposome is similar to that in peripheral nerve myelin.