The role of HDL consisting of SP-40,40, apo A-I, and lipids in the formation of SMAC of complement.
Soluble membrane attack complex (SMAC, SC5b-9) of complement contained apolipoprotein A-I (apo A-I) and lipids. Since SC5b-9 contained no apolipoprotein A-II (apo A-II), the incorporation of apo A-I and lipids into SC5b-9 was not caused by a non-specific binding of high-density lipoprotein (HDL). The incorporation of apo A-I into SC5b-9 was confirmed by a double agar diffusion immuno-assay. SC5b-9 contained one molecule of apo A-I and 3.5% lipids by weight. The composition of the lipids was phospholipid: total cholesterol: triglyceride = 47.5:45.0:7.5, and the ratio of free cholesterol:esterified cholesterol was 22.3:77.7. Since SC5b-7 contained apo A-I and SC5b-9 free of SP-40,40 contained no apo A-I, the HDL consisting of SP-40,40, apo A-I, and lipids was incorporated into SMAC at the stage of SC5b-7 via SP-40,40 as a binding site.
Department of Physiological Chemistry, School of Pharmaceutical Sciences, Showa University, Tokyo.
N H
NH
Choi-Miura
T
T
Sakamoto
T
T
Tobe
Y
Y
Nakano
M
M
Tomita
D016632:Apolipoprotein A-I / Q000032:analysis / Q000378:metabolism; D001798:Blood Proteins / Q000032:analysis / Q000378:metabolism; D015153:Blotting, Western; D051152:Clusterin; D015938:Complement Membrane Attack Complex; D003165:Complement System Proteins / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay; D050356:Lipid Metabolism; D008055:Lipids / Q000032:analysis; D008075:Lipoproteins, HDL / Q000032:analysis* / Q000378:metabolism; D018832:Molecular Chaperones; D011485:Protein Binding
D016632:Apolipoprotein A-I; D001798:Blood Proteins; C495242:CLU protein, human; D051152:Clusterin; D015938:Complement Membrane Attack Complex; D006023:Glycoproteins; D008055:Lipids; D008075:Lipoproteins, HDL; D018832:Molecular Chaperones; C047610:SC5b-9 protein complex; D003165:Complement System Proteins