文章基本信息

标题：N-terminal domain of apolipoprotein B has structural homology to lipovitellin and microsomal triglyceride transfer protein: a “lipid pocket” model for self-assembly of apoB-containing lipoprotein particles
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作者：Jere P. Segrest ; Martin K. Jones ; Nassrin Dashti 等
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：1999
卷号：40
期号：8
页码：1401-1416
语种：English
出版社：American Society for Biochemistry and Molecular Biology
摘要：The process of assembly of apolipoprotein (apo) B-containing lipoprotein particles occurs co-translationally after disulfide-dependent folding of the N-terminal domain of apoB but the mechanism is not understood. During a recent database search for protein sequences that contained similar amphipathic β strands to apoB-100, four vitellogenins, the precursor form of lipovitellin, an egg yolk lipoprotein, from chicken, frog, lamprey, and C. elegans appeared on the list of candidate proteins. The X-ray crystal structure of lamprey lipovitellin is known to contain a “lipid pocket” lined by antiparallel amphipathic β sheets. Here we report that the first 1000 residues of human apoB-100 (the α₁ domain plus the first 200 residues of the β₁ domain) have sequence and amphipathic motif homologies to the lipid-binding pocket of lamprey lipovitellin. We also show that most of the α₁ domain of human apoB-100 has sequence and amphipathic motif homologies to human microsomal triglyceride transfer protein (MTP), a protein required for assembly of apoB-containing lipoproteins. Based upon these results, we suggest that an LV-like “proteolipid” intermediate containing a “lipid pocket” is formed by the N-terminal portion of apoB alone or, more likely, as a complex with MTP. This intermediate produces a lipid nidus required for assembly of apoB-containing lipoprotein particles; pocket expansion through the addition of amphipathic β strands from the β₁ domain of apoB results in the formation of a progressively larger high density lipoprotein (HDL)-like, then very low density lipoprotein (VLDL)-like, spheroidal lipoprotein particle. —Segrest, J. P., M. K. Jones, and N. Dashti. N-terminal domain of apolipoprotein B has structural homology to lipovitellin and microsomal triglyceride transfer protein: a “lipid pocket” model for self-assembly of apoB-containing lipoprotein particles. J. Lipid Res. 1999. 40: 1401–1416.
关键词：plasma apolipoproteins ; LOCATE ; microsomal triglyceride transfer protein (MTP) ; amphipathic β sheets ; amphipathic α helixes ; co-translational ; vitellogenin ; lipovitellin precursor ; α₁ domain ; β₁ domain