Purification of liver membranes highly enriched in phosphatidylinositol kinase.
Membranes highly enriched in phosphatidylinositol (PtdIns) kinase were purified from rat liver by sucrose density gradient centrifugation of a plasma membrane-depleted microsomal fraction. PtdIns kinase-containing membranes had a lower density than membranes containing Golgi and plasma membrane markers, both in sucrose and Nycodenz gradients, without being completely resolved from these other membranes. They also had a lower density than an endosomal marker. Furthermore, lectin affinity partitioning showed that PtdIns kinase did not reside in plasma membranes. PtdIns kinase in different membrane fractions was of type II and had similar kinetic properties. We suggest that the isolated membranes are the major site for phosphatidylinositol 4-phosphate formation in the liver cell, and that these membranes are part of the exocytic pathway. Thus, PtdIns kinase might be a convenient marker for the exocytic process.
Olsson
H
H
Biochemistry, University of Lund, Sweden.
Persson
A
A
Jergil
B
B
D019870:1-Phosphatidylinositol 4-Kinase; D002499:Centrifugation, Density Gradient; D002846:Chromatography, Affinity; D007425:Intracellular Membranes / Q000201:enzymology*; D007472:Iohexol; D008099:Liver / Q000201:enzymology* / Q000648:ultrastructure; D010770:Phosphotransferases / Q000302:isolation & purification* / Q000378:metabolism; D013347:Subcellular Fractions
D007472:Iohexol; D010770:Phosphotransferases; D019870:1-Phosphatidylinositol 4-Kinase