Visualization of binding and receptor-mediated uptake of low density lipoproteins by human endothelial cells.
Low density lipoproteins (LDL) were conjugated to colloidal gold for investigation of the ultrastructural aspects of binding and receptor-mediated internalization of LDL by cultured endothelial cells from the human umbilical artery and vein. The number of LDL receptors was increased by preincubation in lipoprotein-depleted serum. When the cells were incubated with LDL-gold particles for 2 h at 4 degrees C, the complexes were found in coated pits as well as in clusters attached to the plasma membrane. Small vesicles containing a few LDL-gold complexes appeared in the cytoplasm close to the plasma membrane when the cells were incubated with the conjugate for 5 min at 37 degrees C. After 15 min at 37 degrees C, larger vesicles with a pale matrix and membrane-orientated LDL-gold complexes were seen. After incubation for 30 min at 37 degrees C, colloidal gold particles were present in dense bodies. Quantification of the binding of LDL-gold complexes to the plasma membrane at 4 degrees C showed no differences between arterial and venous endothelial cells.
D001808:Blood Vessels / Q000378:metabolism* / Q000648:ultrastructure; D002478:Cells, Cultured; D004705:Endocytosis; D004727:Endothelium / Q000378:metabolism / Q000648:ultrastructure; D006046:Gold; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism*; D011973:Receptors, LDL / Q000378:metabolism*
D008077:Lipoproteins, LDL; D011973:Receptors, LDL; D006046:Gold