Characterization of specific [3H]dimethylstaurosporine binding to protein kinase C
| Autor: | J. Scott Pounds, Un Hoi Do, Janet L. Gross, Lynn Enders Stephens, Lisa Johnson Buenaga, William F. Herblin |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Stereochemistry
Tritium Biochemistry Binding Competitive chemistry.chemical_compound Mice Alkaloids medicine Staurosporine Animals Kinase activity Binding site Protein kinase A Protein kinase C Phorbol 12 13-Dibutyrate Protein Kinase C Pharmacology HEPES biology Chemistry fungi Ligand (biochemistry) Enzyme inhibitor biology.protein medicine.drug |
| Zdroj: | Biochemical pharmacology. 40(2) |
| ISSN: | 0006-2952 |
| Popis: | The microbial alkaloid staurosporine is a member of a recently described family of protein kinase inhibitors. [N,N-dimethyl-3H]N-dimethylstaurosporine ([3H]DMS) was prepared from staurosporine by methylation with [3H]methyl iodide. Since staurosporine inhibits protein kinase C (PKC) most potently, the binding of [3H]DMS to this enzyme was examined. Unlike [20-3H(N)]phorbol-12,13-dibutyrate ([3H]PDBu) binding to PKC, [3H]DMS binding was not calcium or phosphatidylserine (PS) dependent. Binding was reversible, with a T1/2 of 69 min and a Koff of 0.01/min. Non-specific binding was defined by a 500-fold molar excess of staurosporine and was less than 10% of total [3H]DMS binding. Specific binding of [3H]DMS was consistent with a single class of binding sites with a Kd of 3.8 +/- 0.6 nM and a Bmax of 675 +/- 30 pmol/g tissue. In competition experiments, staurosporine inhibited [3H]DMS binding with a Ki of 4.7 +/- 0.6 nM, indicating that the two alkaloids had a similar potency for PKC. Also, unlabeled DMS and staurosporine inhibited [3H]DMS binding and PKC catalysis with equivalent potencies. Highly purified rat brain PKC bound equimolar amounts of [3H]PDBu and [3H]DMS. In contrast, crude rat brain PKC, which had been proteolysed to generate a PS and Ca2+ independent enzyme (PK-M) retained the ability to bind [3H]DMS, but not [3H]PDBu. In addition, the kinase inhibitors K-252a and H-7 [1-(5-isoquinolinesulfonyl)-2-methylpiperazine] inhibited [3H]DMS binding, whereas PDBu did not. These results indicate that [3H]DMS is a useful ligand to identify catalytic inhibitors of kinase activity and to explore their mechanisms of action. |
| Databáze: | OpenAIRE |
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