Abstract |
The phosphorylation of lipocortin (a substrate of EGF-receptor kinase, and a putative phospholipase A2 inhibitor) was examined in T51B cells. By using Western blot procedures and antisera specific to lipocortin I, we found that most immunoreactive lipocortin I was located in the cytosol (lipocortin(cvt] of cells extracted in Ca2+-free buffers These cells however had another pool of immunoreactive lipocortin I located in the particulate fraction that was Triton X-100 extractable (lipocortin(mem]. Increasing Ca2+ concentrations in the extraction buffer resulted in more lipocortin(mem) recovered. In vitro phosphorylation of endogenous proteins demonstrated that lipocortin I became phosphorylated in a Ca2+ and phosphatidylserine-dependent manner, suggesting an involvement of protein kinase C. Treatment of cells with 100 ng/ml 12-0-tetradecanoylphorbol-13-acetate (TPA) but not with 4 alpha-phorbol 12,13-didecanoate (4 alpha-PDD) resulted in the in vitro phosphorylation of lipocortin(mem) by protein kinase C. TPA also increased the phosphorylation of lipocortin(mem) in [32P]phosphate-labeled cells.
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Authors | R Campos-Gonzalez, M Kanemitsu, A L Boynton |
Journal | Experimental cell research
(Exp Cell Res)
Vol. 184
Issue 2
Pg. 287-96
(Oct 1989)
ISSN: 0014-4827 [Print] United States |
PMID | 2530098
(Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- Annexins
- Calcium-Binding Proteins
- Carcinogens
- Polyethylene Glycols
- Octoxynol
- Protein Kinase C
- Phospholipases
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Topics |
- Animals
- Annexins
- Calcium-Binding Proteins
(metabolism)
- Carcinogens
(pharmacology)
- Cells, Cultured
- Cytosol
(metabolism)
- Epithelial Cells
- Epithelium
(drug effects, metabolism)
- Liver
(cytology, drug effects, metabolism)
- Octoxynol
- Phospholipases
(antagonists & inhibitors)
- Phosphorylation
- Polyethylene Glycols
- Protein Kinase C
(analysis, metabolism, pharmacology)
- Rats
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