title: Absence of filipin-sterol complexes from large coated pits on the surface of culture cells.
abstract: Monolayer cultures of normal or transformed fibroblasts and of liver cells fixed in a glutaraldehyde solution containing 300 microM filipin, a sterol-specific polyene antibiotic, were freeze-fractured to study the distribution of cholesterol within their plasma membranes. Filipin-sterol complexes, recognizable as 25- to 30-nm protuberances scattered in the fracture face of plasma membrane, were absent from invaginations corresponding to large, bristle-coated pits (and possibly also from small, flask-shaped invaginations). These results suggest that invaginating regions on the cell surface are specialized plasma membrane domains with a lower cholesterol content than the surrounding membrane. The localized change in membrane fluidity due to the low cholesterol concentration could play a role in endocytosis.
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism*; D004705:Endocytosis; D005372:Filipin / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism*; D051379:Mice
chemical_list: D006023:Glycoproteins; D008563:Membrane Lipids; D005372:Filipin; D002784:Cholesterol