FEBS Letters | |
Comparison of the specificities of p70 S6 kinase and MAPKAP kinase‐1 identifies a relatively specific substrate for p70 S6 kinase: the N‐terminal kinase domain of MAPKAP kinase‐1 is essential for peptide phosphorylation | |
Barry Caudwell, F.1  Dalby, Kevin N.1  Cohen, Patricia T.W.1  Leighton, Ian A.1  Cohen, Philip1  | |
[1] MRC Protein Phosphorylation Unit, Department of Biochemistry, University of Dundee, Dundee DD1 4HN, Scotland, UK | |
关键词: S6 kinase; MAP kinase; Protein kinase; Ribosomal protein S6; Protein phosphorylation; Site-directed mutagenesis; | |
DOI : 10.1016/0014-5793(95)01170-J | |
学科分类:生物化学/生物物理 | |
来源: John Wiley & Sons Ltd. | |
【 摘 要 】
xxR/KxRxxSxx sequences were phosphorylated with high efficiency by both p70 S6 kinase (p70S6K) and MAPKAP kinase-1. The best substrate for MAPKAP kinase-1 (KKKNRTLSVA) was phosphorylated with a K m of 0.17 μM, and the best substrate for p70S6K (KKRNRTLSVA) with a K m of 1.5 μM. The requirement of both enzymes for Arg/Lys at position n-5 could be partially replaced by inserting basic residues at other positions, especially by an Arg at n - 2 or n - 4. MAPKAP kinase-1 (but not p70S6K) tolerated lack of any residue at n - 5 if Arg was present at n - 2 and n - 3. p70S6K (but not p90S6K) tolerated Thr at position n and absence of any residue at n + 2. The peptide KKRNRTLTV, which combined these features, was relatively selective for p70S6K having a 50-fold higher V max/K m than MAPKAP kinase-1. Inactivation of the N-terminal kinase domain of MAPKAP kinase-1, which is 60% identical to p70S6K, abolished activity towards all peptides tested, but the enzyme retained 30–40% of its activity if the C-terminal kinase domain was inactivated.
【 授权许可】
Unknown
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