Phosphorylation and redistribution of the phosphatidylinositol-transfer protein in phorbol 12-myristate 13-acetate- and bombesin-stimulated Swiss mouse 3T3 fibroblasts

By immunofluorescence microscopy it was shown that the phosphatidylinositol-transfer protein (PI-TP) becomes associated with the Golgi membranes when confluent (quiescent) Swiss mouse 3T3 fibroblast cells are stimulated with phorbol 12-myristate 13-acetate (PMA) and bombesin. Dibutyryl cyclic AMP or...

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Bibliographic Details
Published in:Biochemical journal 1993-04, Vol.291 (2), p.649-656
Main Authors: SNOEK, G. T, WESTERMAN, J, WOUTERS, F. S, WIRTZ, K. W. A
Format: Article
Language:English
Subjects:
3T3 Cells - drug effects
3T3 Cells - metabolism
3T3 Cells - ultrastructure
Animals
Biological and medical sciences
Bombesin - pharmacology
Bucladesine - pharmacology
Carrier Proteins - metabolism
Cell physiology
Dexamethasone - pharmacology
Fluorescent Antibody Technique
Fundamental and applied biological sciences. Psychology
Golgi Apparatus - metabolism
Immunosorbent Techniques
Membrane Proteins
Mice
Microscopy, Fluorescence
Molecular and cellular biology
Phospholipid Transfer Proteins
Phosphorylation
Responses to growth factors, tumor promotors, other factors
Tetradecanoylphorbol Acetate - pharmacology
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Summary:By immunofluorescence microscopy it was shown that the phosphatidylinositol-transfer protein (PI-TP) becomes associated with the Golgi membranes when confluent (quiescent) Swiss mouse 3T3 fibroblast cells are stimulated with phorbol 12-myristate 13-acetate (PMA) and bombesin. Dibutyryl cyclic AMP or dexamethasone had no effect on the intracellular redistribution of PI-TP. In exponentially growing cells and in serum-starved (semi-quiescent) cells, PI-TP is already associated with Golgi structures. Stimulation of semi-quiescent cells by PMA resulted in a rapid redistribution of PI-TP. A similar yet slower response was observed after stimulation with bombesin. Stimulation of semi-quiescent 3T3 cells by PMA significantly increased the phosphorylation of PI-TP, as shown by immunoprecipitation of PI-TP from pre-labelled cells. No significant increase in phosphorylation of PI-TP was observed after stimulation of these cells by bombesin. Purified PI-TP was shown to be a substrate for protein kinase C in vitro. The possibility that the phosphorylation of PI-TP after activation of protein kinase C is involved in the observed redistribution of PI-TP is discussed.
ISSN:0264-6021
1470-8728
DOI:10.1042/bj2910649