Cyclic Nucleotide-independent protein kinases from rabbit reticulocytes. Identification and characterization of a protein kinase activated by proteolysis

A proteolytically activated, cyclic nucleotide-independent protein kinase (PAK I) was identified and isolated from the postribosomal supernatant of rabbit reticulocytes. A lack of stimulation by cAMP and resistance of the proteolytically activated form to inhibition by the heat-stable inhibitor prot...

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Bibliographic Details
Published in:The Journal of biological chemistry 1981-11, Vol.256 (22), p.11558-11564
Main Authors: Tahara, S M, Traugh, J A
Format: Article
Language:English
Subjects:
Animals
Cations, Divalent
Cyclic AMP - pharmacology
Enzyme Activation
Kinetics
Magnesium - pharmacology
Magnesium Chloride
Nucleotides, Cyclic - pharmacology
Phosphorylation
protein kinase
Protein Kinases - blood
Protein Kinases - isolation & purification
purification
Rabbits
reticulocytes
Reticulocytes - enzymology
Trypsin - pharmacology
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Summary:A proteolytically activated, cyclic nucleotide-independent protein kinase (PAK I) was identified and isolated from the postribosomal supernatant of rabbit reticulocytes. A lack of stimulation by cAMP and resistance of the proteolytically activated form to inhibition by the heat-stable inhibitor protein of the cAMP-dependent protein kinase indicated that PAK I was not a cAMP-dependent protein kinase; in addition, the enzyme was chromatographically distinct from the latter. The holoenzyme was partially purified. PAK I required high concentrations of Mg super(2+) (45 mM) and 2-mercaptoethanol (20 mM) for maximal activity with mixed histone with an apparent K sub(m) of 0.51 mg/ml. The enzyme utilized only ATP as a phosphoryl donor with a K sub(m) apparent of 0.6 mM for the nucleotide.
ISSN:0021-9258
DOI:10.1016/S0021-9258(19)68437-1