TY - JOUR
T1 - Comparison of the specificities of p70 S6 kinase and MAPKAP kinase-1 identifies a relatively specific substrate for p70 S6 kinase
T2 - the N-terminal kinase domain of MAPKAP kinase-1 is essential for peptide phosphorylation
AU - Leighton, Ian A.
AU - Dalby, Kevin N.
AU - Barry Caudwell, F.
AU - Cohen, Patricia T.W.
AU - Cohen, Philip
PY - 1995/11/20
Y1 - 1995/11/20
N2 - 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 Km of 0.17 μM, and the best substrate for p70S6K (KKRNRTLSVA) with a Km 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 Vmax/Km 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.
AB - 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 Km of 0.17 μM, and the best substrate for p70S6K (KKRNRTLSVA) with a Km 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 Vmax/Km 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.
KW - MAP kinase
KW - Protein kinase
KW - Protein phosphorylation
KW - Ribosomal protein S6
KW - S6 kinase
KW - Site-directed mutagenesis
UR - http://www.scopus.com/inward/record.url?scp=0028875925&partnerID=8YFLogxK
U2 - 10.1016/0014-5793(95)01170-J
DO - 10.1016/0014-5793(95)01170-J
M3 - Article
C2 - 7498520
AN - SCOPUS:0028875925
VL - 375
SP - 289
EP - 293
JO - FEBS Letters
JF - FEBS Letters
SN - 0014-5793
IS - 3
ER -