Cytoplasmic Localization of Mitogen-activated Protein Kinase Kinase Directed by Its NH2-terminal, Leucine-rich Short Amino Acid Sequence, Which Acts as a Nuclear Export Signal

doi:10.1074/jbc.271.33.20024

Cytoplasmic Localization of Mitogen-activated Protein Kinase Kinase Directed by Its NH₂-terminal, Leucine-rich Short Amino Acid Sequence, Which Acts as a Nuclear Export Signal*

From the Department of Genetics and Molecular Biology, Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-01, Japan

^‡To whom correspondence should be addressed. Fax: 81-75-751-3992.

Abstract

Mitogen-activated protein kinase (MAPK) is activated in cytoplasm in response to extracellular signals and then is translocated to nucleus. A directed activator for MAPK, MAPK kinase (MAPKK), stays in cytoplasm to transmit the signal from the plasma membrane to MAPK. Here we show that MAPKK contains a short amino acid sequence in the N-terminal region (residues 32-44), which acts as a nuclear export signal (NES) and thus is required for cytoplasmic localization of MAPKK. This NES sequence of MAPKK, like that of protein kinase inhibitor of cAMP-dependent protein kinase or Rev, is rich in leucine residues, which are crucial for the NES activity. Furthermore, the NES peptide of protein kinase inhibitor, as well as the NES peptide of MAPKK, inhibited the nuclear export of ovalbumin conjugated to the NES peptide of MAPKK. These results may suggest a common mechanism of nuclear export using a general leucine-rich NES.

Footnotes

↵* This work was supported by grants-in-aid from the Ministry of Education, Science and Culture of Japan. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

MAPK

mitogen-activated protein kinase

MAPKK

MAP kinase kinase

PKI

protein kinase inhibitor

NES

nuclear export signal

WT

wild type

GST

glutathione S-transferase

BSA

bovine serum albumin

RITC

tetramethyl rhodamine isothiocyanate

PBS

phosphate-buffered saline

OV

ovalbumin

L-OV

L peptide-conjugated OV

A-OV

A peptide-conjugated OV

SESE

S218E/S222E

Δ-SESE

Δ(residues 32-51)SESE

SMCC

succinimidyl 4-(N-maleimidomethyl)cylohexane-1-carboxylate.
- Received March 8, 1996.
- Revision received April 23, 1996.