PubMed Journals: J Biol Chem
Source: PMID: 7592979
⇦ ⇨ J Biol Chem. 1995 Nov 10;270(45):27213-21.
Constitutive activation of mitogen-activated
protein kinase-activated protein kinase
2 by mutation of phosphorylation sites and
an A-helix motif.
Engel K(1), Schultz H, Martin F, Kotlyarov
A, Plath K, Hahn M, Heinemann U, Gaestel
(1) Max-Delbrück-Centrum für Molekulare
Medizin, Berlin, Federal Republic of Germany.
A recently described downstream target of
mitogen-activated protein kinases (MAPKs)
is the MAPK-activated protein (MAPKAP) kinase
2 which has been shown to be responsible
for small heat shock protein phosphorylation.
We have analyzed the mechanism of MAPKAP
kinase 2 activation by MAPK phosphorylation
using a recombinant MAPKAP kinase 2-fusion
protein, p44MAPK and p38/40MAPK in vitro
and using an epitope-tagged MAPKAP kinase
2 in heat-shocked NIH 3T3 cells. It is demonstrated
that, in addition to the known phosphorylation
of the threonine residue carboxyl-terminal
to the catalytic domain, Thr-317, activation
of MAPKAP kinase 2 in vitro and in vivo
is dependent on phosphorylation of a second
threonine residue, Thr-205, which is located
within the catalytic domain and which is
highly conserved in several protein kinases.
Constitutive activation of MAPKAP kinase
2 is obtained by replacement of both of
these threonine residues by glutamic acid.
A constitutively active form of MAPKAP kinase
2 is also obtained by deletion of a
carboxyl-terminal region containing Thr-317
and the A-helix motif or by replacing the
conserved residues of the A-helix. These
data suggest a dual mechanism of MAPKAP
kinase 2 activation by phosphorylation of
Thr-205 inside the catalytic domain and
by phosphorylation of Thr-317 outside the
catalytic domain involving an autoinhibitory
PMID: 7592979 [Indexed for MEDLINE]