A cholesteryl ester transfer complex in human plasma.
Immunoadsorption affinity chromatography has been used to define the structure of lipoproteins in human plasma containing lecithin:cholesterol acyltransferase (EC 2.3.1.43) (LCAT) and transfer protein (apo D). The whole of LCAT was absorbed by antibodies specific for apo D and for apo A-1, indicating that the enzyme is present in plasma exclusively as a complex with its cofactor (apo A-1) and product transfer protein (apo D). About 80% of apo D (but no LCAT) was removed by antibody to apo A-2, indicating the presence of most of apo D in the form of an enzyme-free complex will apo A-1 and apo A-2. After removal of LCAT with antibody to apo D, plasma was unreactive as a substrate with isolated LCAT, but substrate activity was generated by ultracentrifugal flotation with either intact or adsorbed plasma. The apparent stoichiometry of the complex with LCAT (LCAT:apo A-1:apo D) was 1.0:0.9:1.8; that of the complex containing apo A-1, apo A-2, and apo D was 3.9:2.2:1.0.
D016632:Apolipoprotein A-I; D016633:Apolipoprotein A-II; D001053:Apolipoproteins / Q000097:blood* / Q000276:immunology / Q000378:metabolism; D001055:Apolipoproteins B; D053399:Apolipoproteins D; D002352:Carrier Proteins / Q000378:metabolism; D002788:Cholesterol Esters / Q000378:metabolism; D002846:Chromatography, Affinity; D006801:Humans; D007163:Immunosorbent Techniques; D008075:Lipoproteins, HDL / Q000032:analysis / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000378:metabolism; D008079:Lipoproteins, VLDL / Q000378:metabolism; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000097:blood* / Q000276:immunology / Q000378:metabolism
D016632:Apolipoprotein A-I; D016633:Apolipoprotein A-II; D001053:Apolipoproteins; D001055:Apolipoproteins B; D053399:Apolipoproteins D; D002352:Carrier Proteins; D002788:Cholesterol Esters; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D007862:Phosphatidylcholine-Sterol O-Acyltransferase