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Updated: Jun 26, 2026

A Guide to Production, Crystallization, and Structure Determination of Human IKK1/α
Published on: November 2, 2018
Enzymatic characteristics of a Ser/Thr protein kinase, SpkA, from Myxococcus xanthus
Yoshio Kimura1, Aoi Kakemizu, Yuuko Matsubara
1Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki-cho, Kagawa 761-0795, Japan. kimura@ag.kagawa-u.ac
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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