Kimura Y, Kakemizu A, Matsubara Y, Takegawa K. Enzymatic characteristics of a Ser/Thr protein kinase, SpkA, from Myxococcus xanthus.
J Biosci Bioeng 2009;
107:10-5. [PMID:
19147102 DOI:
10.1016/j.jbiosc.2008.08.002]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Accepted: 08/26/2008] [Indexed: 11/26/2022]
Abstract
Two Ser/Thr protein kinases, SpkA and SpkB, selected from Myxococcus xanthus based on amino acid sequence similarities with the catalytic subunits of cAMP-dependent protein kinases (PKA) were synthesized using a cell-free protein synthesis system. In various protein kinase assays, purified StkA and StkB showed their highest protein kinase activities in a PKA assay using the selective PKA substrate Kemptide and in a protein kinase C (PKC) assay using the selective PKC substrate neurogranin((28-43)), respectively. SpkA had apparent K(m) values of 45 microM and 37 microM for Kemptide and ATP, respectively. Phosphorylation of Kemptide was inhibited by a specific PKA inhibitor peptide, PKI(5-24), and the IC(50) and K(i) values for inhibition of the SpkA activity were 117 nM and 36 nM, respectively.
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