title: A single copy of apolipoprotein B-48 is present on the human chylomicron remnant.
abstract: Individuals homozygous for the e2 allele encoding apolipoprotein E exhibit a remnant removal defect and accumulate substantial levels of intestinally derived particles containing apolipoprotein B-48 (apoB-48). Such lipoproteins were isolated from the plasma of E2/E2 individuals, and further purified by affinity chromatography using a polyclonal antibody specific for selective binding and removal of apoB-100-containing lipoproteins. The unbound lipoproteins, termed chylomicron remnants, were particles with average hydrated diameters of 31.2 nm as determined by dynamic light scattering. They contained apoB-48 and ApoE as their only protein components. The number of apoB-48 molecules on each lipoprotein was assessed by counting the number of antibody molecules bound to the surface of the chylomicron remnants, using either a monoclonal antibody specific for a single epitope on apoB-48 or a mixture of two such monoclonal antibodies specific for widely separated epitopes. The results of this analysis seem unambiguous: no more than one apoB-48 resides on the chylomicron remnant. Because apoB appears to be unable to transfer among lipoprotein particles, it may be inferred that nascent chylomicrons also contain a single copy of apoB-48.
authors.affiliation: Department of Chemistry and Biochemistry, University of California-Los Angeles 90095-1569, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Phillips
authors.forename: C
authors.initials: C
authors.lastname: Pullinger
authors.forename: I
authors.initials: I
authors.lastname: Kroes
authors.forename: J
authors.initials: J
authors.lastname: Kroes
authors.forename: D A
authors.initials: DA
authors.lastname: Hardman
authors.forename: G
authors.initials: G
authors.lastname: Chen
authors.forename: L K
authors.initials: LK
authors.lastname: Curtiss
authors.forename: M M
authors.initials: MM
authors.lastname: Gutierrez
authors.forename: J P
authors.initials: JP
authors.lastname: Kane
authors.forename: V N
authors.initials: VN
authors.lastname: Schumaker
mesh_terms: D000911:Antibodies, Monoclonal / Q000032:analysis / Q000276:immunology / Q000302:isolation & purification; D053299:Apolipoprotein B-100; D053283:Apolipoprotein B-48; D001055:Apolipoproteins B / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D002846:Chromatography, Affinity; D002914:Chylomicrons / Q000737:chemistry* / Q000276:immunology / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000032:analysis / Q000276:immunology; D006801:Humans; D016253:Microscopy, Immunoelectron; D016622:Silver Staining
chemical_list: D000911:Antibodies, Monoclonal; D053299:Apolipoprotein B-100; D053283:Apolipoprotein B-48; D001055:Apolipoproteins B; D002914:Chylomicrons; D000939:Epitopes