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Auto‐inhibition of Ca 2+ /calmodulin‐dependent protein kinase II by its ATP‐binding domain
Author(s) -
Lengyel I.,
Nairn A. C.,
McCluskey A.,
Tóth G.,
Penke B.,
Rostas J. A. P.
Publication year - 2001
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2001.00139.x
Subject(s) - calmodulin , biochemistry , enzyme , protein kinase a , kinase , alanine , chemistry , binding site , amino acid , biology
Ca 2+ /calmodulin dependent protein kinase (CaMPK) II is a key enzyme in many physiological processes. The enzyme is inactive unless Ca 2+ /CaM binds to it. In this inactive form CaMPK‐II does not bind ATP suggesting that the ATP‐binding domain is involved in an intramolecular interaction. We show here that F12, a 12 amino acid long peptide fragment of the ATP‐binding domain (CaMPK‐II 23–34 , GAFSVVRRCVKV) can inhibit the Ca 2+ /CaM‐dependent activity (IC 50 of 3 µ m ) but has no effect on the Ca 2+ /CaM‐independent activity of CaMPK‐II. Kinetic analysis exhibited mixed inhibition with respect to autocamtide‐2 and ATP. The inhibition by F12 showed specificity towards CaMPK‐II, but also inhibited CaMPK‐I (IC 50 = 12.5 µ m ), while CaMPK‐IV (IC 50 = 85 µ m ) was inhibited poorly and cAMP‐dependent protein kinase (PKA) was not inhibited. Substitution of phenylalanine at position 25 to alanine (A12), had little effect on the inhibition of different Ca 2+ /CaM‐dependent protein kinases, suggesting that phenylalanine 25 does not play a crucial role in the interactions involving F12. Thus the molecular interactions involving the ATP‐binding domain appears to play a role in the regulation of nonphosphorylated CaMPK‐II activity.