Secretion of a lipid transfer protein by human monocyte-derived macrophages.
Human monocyte-derived macrophages in culture were shown to synthesize and secrete a lipid transfer protein. The human monocyte-derived macrophage transfer protein showed the following characteristics: (i) linear secretion rate over a 24-h period, which was blocked completely by cycloheximide and stimulated by phorbol myristate acetate (67% increase over nonstimulated values); (ii) apparent Mr = approximately 62,000 off Sephacryl S-200; (iii) isoelectric point of 5.0; (iv) binding to phenyl-Sepharose, but not to heparin-Sepharose; (v) facilitation of the transfer of both neutral lipids (cholesteryl esters and triglycerides) and phosphatidylcholine between high density lipoproteins and d less than 1.063 g/ml lipoproteins; and (vi) thermal stability (stable for 1 h at 56 degrees C). The last five of these properties are similar to those of the plasma lipid transfer protein. Thus, macrophages secrete a lipid transfer protein that closely resembles the neutral lipid transfer protein found in human plasma and may be a source of this plasma protein in vivo.
D002352:Carrier Proteins / Q000097:blood / Q000302:isolation & purification / Q000378:metabolism*; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D006801:Humans; D007526:Isoelectric Point; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D008970:Molecular Weight; D009000:Monocytes / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D002352:Carrier Proteins; C030363:lipid transfer protein; D003513:Cycloheximide; D013755:Tetradecanoylphorbol Acetate