J. Biol. Chem., Vol. 259, Issue 11, 6952-6957, Jun, 1984

Characterization of antigenic determinants on human solubilized apolipoprotein B. Conformational requirements for lipids

YL Marcel, M Hogue, PK Weech and RW Milne

The expression of low density lipoprotein (LDL) antigenic determinants in the delipidated and solubilized apolipoprotein B (apo-B) free of sodium dodecyl sulfate (SDS) has been studied. Of the six distinct determinants which react with previously characterized monoclonal antibodies against LDL (Milne, R.W., Theolis , R., Jr., Verdery , R.B., and Marcel , Y.L. (1983) Arteriosclerosis 3, 23-30), only one, that recognized by antibody 1D1 , was expressed on the soluble apo-B, indicating that soluble apo-B may be partly denatured. The average immunoreactivity of apo-B with antibody 1D1 was similar to or lower than that of intact LDL (mean 36%, range 93-20%). Therefore, delipidation and solubilization did not expose on apo-B any additional site reactive with 1D1 . When apo-B was equilibrated with either SDS micelles or with cholesterol-lecithin liposomes, the immunoreactivity of the determinant recognized by antibody 2D8 was partially regenerated, but not that of the others. In contrast, incubation of apo- B with microemulsions containing a hydrophobic core of cholesteryl esters also restored the antigenicity of the determinants reacting with antibodies 3F5 , 4G3 , and 5E11 . However, the regeneration of these antigenic determinants could only be achieved when solubilized apo-B was treated with SDS prior to equilibration with microemulsion preparations. In conclusion, three types of antigenic determinants have been identified on apo-B. The first type, such as that recognized by antibody 1D1 , is expressed both on LDL and on apo-B and is constituted by the primary and secondary structure of apo-B. The second type, an example being that recognized by 2D8 , is a conformational determinant which requires the presence of amphipathic lipids such as lecithin and cholesterol or SDS micelles. The third type, which reacts with antibodies 3F5 , 4G3 , and 5E11 , represents different conformational determinants which require the association of apo-B with lipid structures having a cholesteryl ester hydrophobic core. It may be significant that the latter determinants are those close to the LDL receptor-binding site on apo-B and that this domain of apo-B has a complex tertiary and quaternary structure as evidenced by the conformational requirements of the antigenic determinants.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				X. Wang, V. Chauhan, A. T. Nguyen, J. Schultz, J. Davignon, S. G. Young, J. Boren, T. L. Innerarity, H. Rutai, and R. W. Milne Immunochemical evidence that human apoB differs when expressed in rodent versus human cells J. Lipid Res., March 1, 2003; 44(3): 547 - 553. [Abstract] [Full Text] [PDF]

				J. L. Dixon, J. Biddle, C.-m. Lo, J. D. Stoops, H. Li, N. Sakata, and T. E. Phillips Apolipoprotein B Is Synthesized in Selected Human Non-hepatic Cell Lines But Not Processed into Mature Lipoprotein J. Histochem. Cytochem., May 1, 2002; 50(5): 629 - 640. [Abstract] [Full Text] [PDF]

				X. Wang, R. Pease, J. Bertinato, and R. W. Milne Well-Defined Regions of Apolipoprotein B-100 Undergo Conformational Change During Its Intravascular Metabolism Arterioscler. Thromb. Vasc. Biol., May 1, 2000; 20(5): 1301 - 1308. [Abstract] [Full Text] [PDF]

				X. Wang, R. Bucala, and R. Milne Epitopes close to the apolipoprotein B low density lipoprotein receptor-binding site are modified by advanced glycation end products PNAS, June 23, 1998; 95(13): 7643 - 7647. [Abstract] [Full Text] [PDF]

				R. S. McLeod, Y. Wang, S. Wang, A. Rusinol, P. Links, and Z. Yao Apolipoprotein B Sequence Requirements for Hepatic Very Low Density Lipoprotein Assembly. EVIDENCE THAT HYDROPHOBIC SEQUENCES WITHIN APOLIPOPROTEIN B48 MEDIATE LIPID RECRUITMENT J. Biol. Chem., August 2, 1996; 271(31): 18445 - 18455. [Abstract] [Full Text] [PDF]

				S. Wang, R. S. McLeod, D. A. Gordon, and Z. Yao The Microsomal Triglyceride Transfer Protein Facilitates Assembly and Secretion of Apolipoprotein B-containing Lipoproteins and Decreases Cotranslational Degradation of Apolipoprotein B in Transfected COS-7 Cells J. Biol. Chem., June 14, 1996; 271(24): 14124 - 14133. [Abstract] [Full Text] [PDF]