Casein kinase II β-subunit inhibits the activity of the catalytic α-subunit in the absence of salt

T. Tiganis, C. M. House, B. E. Kemp

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Casein kinase II (CKII) has a subunit structure α2β2 where α is the catalytic subunit. Recombinant Drosophila casein kinase 11 α-subunit expressed in insect cells is inhibited by NaCl, thermally labile and inactivated by binding to plastic. In the presence of detergent (Tween 80) recombinant α-subunit has a kcat of 249 -1 (Km 170 μM) for the peptide substrate RRRDDDSDDDNH2, compared to recombinant Drosophila CKII with a kcat of 71 min-1 (per mol α) (Km 42 μM) and bovine CKII with a kcat of 123 min-1 (per mol α) (Km 45 μM) when measured in the absence of NaCl. The kcat values of bovine CKII and recombinant Drosophila CKII measured in the presence of 150 mM NaCl were 429 min-1 (per mol α) (Km 82 μM) and 204 min-1 (per mol α) (Km 51 μM), respectively. Since the kcat for the Drosophila α-subunit is approx. 3-fold greater than the Drosophila CKII measured in the absence of added salt these results indicate that the β-subunit acts primarily as an inhibitory subunit.

Original languageEnglish
Pages (from-to)282-289
Number of pages8
JournalBiochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology
Issue number2
Publication statusPublished - 8 Dec 1993
Externally publishedYes


  • (Drosophila)
  • Casein kinase II
  • Recombinant
  • Salt
  • Subunit

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