A common binding site on the microsomal triglyceride transfer protein for apolipoprotein B and protein disulfide isomerase

Bradbury,P.; Mann,C.J.; Kochl,S.; Anderson,T.A.; Chester,S.A.; Hancock,J.M.; Ritchie,P.J.; Amey,J.; Harrison,G.B.; Levitt,D.G.; Banaszak,L.J.; Scott,J.; Shoulders,C.C.
The assembly of triglyceride-rich lipoproteins requires the formation in the endoplasmic reticulum of a complex between apolipoprotein B (apoB), a microsomal triglyceride transfer protein (MTP), and protein disulfide isomerase (PDI). In the MTP complex, the amino-terminal region of MTP (residues 22-303) interacts with the amino-terminal region of apoB (residues 1-264). Here, we report the identification and characterization of a site on apoB between residues 512 and 721, which interacts with residues 517-603 of MTP. PDI binds in close proximity to this apoB binding site on MTP. The proximity of these binding sites on MTP for PDI and amino acids 512-721 of apoB was evident from studies carried out in a yeast two-hybrid system and by co-immunoprecipitation. The expression of PDI with MTP and apoB16 (residues 1-721) in the baculovirus expression system reduced the amount of MTP co-immunoprecipitated with apoB by 73%. The interaction of residues 512-721 of apoB with MTP facilitates lipoprotein production. Mutations of apoB that markedly reduced this interaction also reduced the level of apoB-containing lipoprotein secretion
J Biol.Chem 1999 274(5):3159-3164
Tags: 99115664; acid; Amino Acid Sequence; Amino Acids; animal; Apolipoproteins B; Binding Sites; Caenorhabditis elegans; Carrier Proteins; Drosophila melanogaster; EXPRESSION; human; identification; Lampreys; metabolism; Microsomes; Models,Molecular; molecular sequence data; Mutation; Protein; Protein Binding; Protein Disulfide-Isomerase; Sequence Alignment; Xenopus laevis
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