title: The purification of plasma membranes from WI-38 fibroblasts: effects of ageing on their composition.
abstract: A three-step method for the purification of plasma membranes from WI-38 fibroblasts was developed thus allowing the recovery of 36--44% of the plasma membrane. Except in the case of galactosyltransferase, the activity of the contaminating enzymes was very low. Morphological observations confirm the presence of a homogeneous population of vesicles. Preparations obtained from young and old cell cultures were compared for their enzymatic and protein contents. With ageing the activity of 5-nucleotidase significantly increases whereas that of alkaline phosphodiesterase I decreases. Out of the 26 components detected after sodium dodecyl sulphate polyacrylamide gel electrophoresis, four decreased but only one increased. Cellular ageing seems to fulfil a specific and localized effect on the plasma membrane.
mesh_terms: D002458:Cell Fractionation / Q000379:methods*; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D009708:Nucleotidases / Q000378:metabolism; D043264:Phosphodiesterase I; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D013997:Time Factors
chemical_list: D007527:Isoenzymes; D008565:Membrane Proteins; D009708:Nucleotidases; D010727:Phosphoric Diester Hydrolases; D043264:Phosphodiesterase I