Organization of the phosphoinositide cycle. Assessment of inositol transferase activity in purified plasma membranes.
Experiments were carried out to determine whether or not CDP-diacylglycerol:myo-inositol 3-phosphatidyltransferase (IT) activity (EC 2.7.8.11) could be detected in purified plasma-membrane fractions from WRK-1 rat mammary tumour cells. These cells have previously been shown to have a very active phosphoinositide cycle. Sucrose-density-gradient-purified plasma membranes contained no IT activity that could not be accounted for by endoplasmic-reticulum contamination. However, we also determined that the relative amount of IT activity in endoplasmic reticulum and plasma-membrane fractions could be altered by changing the concentration of detergent in the assay system.
Department of Physiology & Biophysics, N.Y.U. Medical Center, New York.
O M
OM
Santiago
L I
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Rosenberg
M E
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Monaco
D000818:Animals; D051607:CDP-Diacylglycerol-Inositol 3-Phosphatidyltransferase; D002458:Cell Fractionation; D002462:Cell Membrane / Q000201:enzymology*; D002499:Centrifugation, Density Gradient; D003902:Detergents / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000201:enzymology; D007700:Kinetics; D008325:Mammary Neoplasms, Experimental / Q000201:enzymology*; D008565:Membrane Proteins; D010716:Phosphatidylinositols / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism*; D051381:Rats; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology; D017855:Transferases (Other Substituted Phosphate Groups); D014407:Tumor Cells, Cultured
D003902:Detergents; D008565:Membrane Proteins; D010716:Phosphatidylinositols; D010770:Phosphotransferases; D017855:Transferases (Other Substituted Phosphate Groups); D051607:CDP-Diacylglycerol-Inositol 3-Phosphatidyltransferase; C496767:Cdipt protein, rat