Interaction between hepatic microsomal membrane lipids and apolipoprotein A-I.
Incubation of apoprotein A-I (apo-A-I), the major protein component of human high density lipoprotein, with rat liver microsomal membranes under conditions of elevated pH and ionic strength leads to the production of a soluble protein:lipid complex (A-I/MM complex). The A-I/MM complex, as purified by density gradient centrifugation and agarose column chromatography, possesses a lipid composition similar to the hepatic microsomal membrane and a protein/lipid ratio similar to that of plasma high density lipoproteins, but markedly different from that of recombinant particles prepared with synthetic lipids. The A-I/MM complex constitutes a more physiological recombinant particle than can be formed using synthetic lipids and may be a suitable model for the newly assembled intracellular high density lipoproteins. Incubation of the erythrocyte plasma membranes with apo-A-I under the same conditions as used with microsomal membranes fails to generate any lipid:apoprotein complexes. This membrane specificity for forming soluble lipoprotein complexes suggests that the microsomal membranes possess a unique feature, possibly their lipid composition, which render them particularly suitable to serve as lipid donors to the apoproteins which are undergoing assembly within the endoplasmic reticulum/Golgi organelles.
D000818:Animals; D016632:Apolipoprotein A-I; D001053:Apolipoproteins / Q000097:blood / Q000378:metabolism*; D002458:Cell Fractionation; D004910:Erythrocyte Membrane / Q000378:metabolism; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism* / Q000648:ultrastructure; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008297:Male; D008563:Membrane Lipids / Q000302:isolation & purification / Q000378:metabolism*; D008854:Microscopy, Electron; D008862:Microsomes, Liver / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D011919:Rats, Inbred Strains
D016632:Apolipoprotein A-I; D001053:Apolipoproteins; D008075:Lipoproteins, HDL; D008563:Membrane Lipids