Differential release of proteins from bovine fat globule membrane.
Alkaline phosphatase and 5'-nucleotidase are covalently linked to phosphatidylinositol in bovine fat globule membrane, as demonstrated by their release following treatment with phospholipase C specific for phosphatidylinositol. The failure of this treatment to liberate phosphodiesterase I may indicate that it has a variant linkage resistant to release. In a test of exposure at the membrane surface, alkaline phosphatase and phosphodiesterase I, but not 5'-nucleotidase, were released from fat globule membrane by treatment with proteinase K. These apparent differences in accessibilities of membrane surface proteins suggest that attachment to phosphatidylinositol does not necessarily impart greater exposure to proteins with which it is linked.
Malin
E L
EL
Eastern Regional Research Center, U.S. Department of Agriculture, Philadelphia, PA 19118.
Basch
J J
JJ
D015720:5'-Nucleotidase / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism*; D019286:Endopeptidase K; D050356:Lipid Metabolism; D008321:Mammary Glands, Animal / Q000648:ultrastructure*; D008565:Membrane Proteins / Q000378:metabolism*; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010716:Phosphatidylinositols / Q000378:metabolism; D043264:Phosphodiesterase I; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism
D008565:Membrane Proteins; D010716:Phosphatidylinositols; D000469:Alkaline Phosphatase; D015720:5'-Nucleotidase; D010727:Phosphoric Diester Hydrolases; D043264:Phosphodiesterase I; D012697:Serine Endopeptidases; D019286:Endopeptidase K; D043265:Phosphatidylinositol Diacylglycerol-Lyase