title: A correlative study on the topographical distribution of the receptors for low density lipoprotein (LDL) conjugated to colloid gold in cultured human skin fibroblasts employing thin section, freeze-fracture, deep-etching, and surface replication techniques.
abstract: The topographical distribution of the receptors for low-density lipoprotein (LDL) conjugated to colloidal gold on cultured human skin fibroblasts was studied using a surface replication technique following critical point drying. In this correlative study, also employing thin sectioning, freeze-fracture and deep-etching techniques in conjunction with the polyene antibiotic filipin, it could be shown that LDL preferentially binds to certain microdomains of the plasma membrane, the so-called coated pits. The coated pits can be recognized after filipin treatment both on the P face and E face of the membrane, due to the fact that they are free of filipin-sterol complexes. Filipin was also of value in clearly delimiting the structure of nascent coated pits from their surroundings in surface replicas. Using filipin has the effect of increasing the contrast between the smooth surface of a coated pit and the rough surface of the remaining membrane caused by formation of filipin-sterol complexes. This study has shown that there are differences in the topographical distribution and number of gold particles from fibroblast to fibroblast and even between different areas of the same cell. The surface replication technique using goldlabelled LDL provides s suitable method for improving the interpretation of the spatial arrangement of the LDL receptors. The advantages of this technique are discussed in comparison with the methods previously employed to visualize LDL receptors.
mesh_terms: D002462:Cell Membrane / Q000032:analysis* / Q000648:ultrastructure; D002478:Cells, Cultured; D003102:Colloids; D005347:Fibroblasts; D005372:Filipin; D005613:Freeze Etching; D005614:Freeze Fracturing; D006046:Gold; D006801:Humans; D008854:Microscopy, Electron; D011956:Receptors, Cell Surface / Q000032:analysis*; D011973:Receptors, LDL; D012867:Skin
chemical_list: D003102:Colloids; D011956:Receptors, Cell Surface; D011973:Receptors, LDL; D006046:Gold; D005372:Filipin