Lipoproteins in lecithin-cholesterol-acyltransferase(LCAT)-deficiency. II. Further studies on the abnormal high-density-lipoproteins.
The lipoproteins from two sibs with familial lecithin-cholesterol-acyltransferase(LCAT)-deficiency were further characterized.  Comparatively lipoproteins from patients with secondary LCAT-deficiency were studied.  Both groups of patients had particles of unusual size and shape in the alpha1-(HD-2)-lipoprotein subfraction.  The abnormal HDL-2 particles were disk-like in appearance with a major axis of about 180 A and a minor axis of about 40 A and tended to aggregate into long coinlike stacks.  The abnormal HDL-2 particles contained the normal protein constituents of HDL Apo A-I, Apo A-II and Apo C but in addition a major polypeptide with a M.W. of 39000 not seen in significant amounts in normal high-density-lipoproteins.  This polypeptide was found identical in size, isoelectric focusing and immunochemically with an arginine-rich normal polypeptide constituent of very-low-density-lipoproteins designated apoprotein E.  Presence of this protein marker in the HDL allowed the specific immunological detection of the abnormal HDL-2 (LP-E) in plasma.  Further minor biochemical abnormalities were observed in the lipoproteins of the patients with familial LCAT-deficiency.  However, the main protein constituents of their HDL, the Apo A, Apo C and Apo E polypeptides, were found to be identical electrophoretically and by analytical isoelectric focusing with their normal counterparts.  The data suggest that the basic genetic defect in the hereditary disease leads to a deficient activity of the LCAT-enzyme and that all abnormalities in the lipoprotein spectrum are secondary.
D000123:Acetyltransferases / Q000172:deficiency*; D001059:Apoproteins / Q000097:blood; D002784:Cholesterol; D004591:Electrophoresis, Polyacrylamide Gel; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D007525:Isoelectric Focusing; D008052:Lipid Metabolism, Inborn Errors / Q000097:blood* / Q000235:genetics; D008074:Lipoproteins / Q000276:immunology; D008075:Lipoproteins, HDL / Q000097:blood*; D008854:Microscopy, Electron; D008968:Molecular Conformation; D008970:Molecular Weight; D010455:Peptides / Q000032:analysis; D010713:Phosphatidylcholines
D001059:Apoproteins; D008074:Lipoproteins; D008075:Lipoproteins, HDL; D010455:Peptides; D010713:Phosphatidylcholines; D002784:Cholesterol; D000123:Acetyltransferases