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

FEBS Letters

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 (p70^S6K) 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 p70^S6K (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 p70^S6K) tolerated lack of any residue at n - 5 if Arg was present at n - 2 and n - 3. p70^S6K (but not p90^S6K) tolerated Thr at position n and absence of any residue at n + 2. The peptide KKRNRTLTV, which combined these features, was relatively selective for p70^S6K 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 p70^S6K, 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