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Molecular and Cellular Biology, January 2001, p. 249-259, Vol. 21, No. 1
Department of Microbiology and Cancer Center,
School of Medicine, University of Virginia, Charlottesville,
Virginia 22908
Received 20 April 2000/Returned for modification 30 May
2000/Accepted 11 October 2000
Extracellular signal-regulated kinase 1 (ERK1) and ERK2 are
important components in signal transduction pathways involved in many
cellular processes, including cell differentiation and proliferation.
These proteins consist of a central kinase domain flanked by short N-
and C-terminal noncatalytic domains. While the regulation of ERK2 by
sequences within the kinase domain has been extensively studied, little
is known about the small regions outside of the kinase domain. We
performed mutational analysis on the N-terminal, noncatalytic domain of
ERK2 in an attempt to determine its role in ERK2 function and
regulation. Deleting or mutating amino acids 19 to 25 (ERK2-
0270-7306/01/$04.00+0 DOI: 10.1128/MCB.21.1.249-259.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Biochemical and Biological Functions of the
N-Terminal, Noncatalytic Domain of Extracellular Signal-Regulated
Kinase 2
and
19-25)
created an ERK2 molecule that could be phosphorylated in response to
growth factor and serum stimulation in a MEK (mitogen-activated protein
kinase kinase or ERK kinase)-dependent manner but had little kinase
activity and was unable to bind to MEK in vivo. Since MEK acts as a
cytoplasmic anchor for the ERKs, the lack of a MEK interaction resulted
in the aberrant nuclear localization of ERK2-
19-25 mutants in
serum-starved cells. Assaying these mutants for their ability to affect
ERK signaling revealed that ERK2-
19-25 mutants acted in a
dominant-negative manner to inhibit transcriptional signaling through
endogenous ERKs to an Elk1-responsive promoter in transfected COS-1
cells. However, ERK2-
19-25 had no effect on the phosphorylation of
RSK2, an ERK2 cytoplasmic substrate, whereas a nonactivatable ERK
(T183A) that retained these sequences could inhibit RSK2
phosphorylation. These results suggest that the N-terminal domain of
ERK2 profoundly affects ERK2 localization, MEK binding, kinase
activity, and signaling and identify a novel dominant-negative mutant
of ERK2 that can dissociate at least some transcriptional responses
from cytoplasmic responses.
*
Corresponding author. Mailing address: Department of
Microbiology, Box 441, Rm. 216, Jordan Hall, University of Virginia, Charlottesville, VA 22908. Phone: (804) 924-5022. Fax: (804) 982-0689. E-mail: mjw{at}virginia.edu.
Present address: Department of Pathology, College of Physicians and
Surgeons, Columbia University, New York, NY 10032.
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