The phosphatidylinositol transfer protein in 3T3 mouse fibroblast cells is associated with the Golgi system.
By use of indirect immunofluorescence it was shown that the phosphatidylinositol transfer protein (PI-TP) in 3T3 mouse fibroblast cells is associated with the Golgi system. This was concluded from double-labeling experiments with TRITC-labeled Ricin which binds to sugar residues that are specifically processed in the Golgi system. Independent evidence for this association was provided by the fact that dissociation of the Golgi system by brefeldin A was reflected in an extensive redistribution of PI-TP labeling. In addition, PI-TP is localized in the cytoplasm and in the nucleus. In exponentially growing cells an enhanced labeling of PI-TP was observed in the cytosol and in the cytosol and in the Golgi system in comparison with quiescent cells. By Western blot analysis and by transfer activity assays, it was confirmed that the concentration of PI-TP was increased in exponentially growing cells. These results strongly suggest that PI-TP fulfills a role in the functioning of the Golgi complex.
Snoek
G T
GT
Centre for Biomembranes and Lipid Enzymology, State University of Utrecht, The Netherlands.
de Wit
I S
IS
van Mourik
J H
JH
Wirtz
K W
KW
D016475:3T3 Cells / Q000737:chemistry*; D000818:Animals; D002352:Carrier Proteins / Q000032:analysis*; D002467:Cell Nucleus / Q000737:chemistry; D003593:Cytoplasm / Q000737:chemistry; D005455:Fluorescent Antibody Technique; D006056:Golgi Apparatus / Q000737:chemistry*; D006651:Histocytochemistry; D008565:Membrane Proteins; D051379:Mice; D008853:Microscopy / Q000379:methods; D049294:Phospholipid Transfer Proteins
D002352:Carrier Proteins; D008565:Membrane Proteins; D049294:Phospholipid Transfer Proteins