Nuclear Localization and Regulation of Id Protein through an E Protein-mediated Chaperone Mechanism

doi:10.1074/jbc.271.39.23603

Nuclear Localization and Regulation of Id Protein through an E Protein-mediated Chaperone Mechanism*

From the Cancer Research Campaign Department of Gene Regulation, Paterson Institute for Cancer Research, Christie Hospital National Health Service Trust, Wilmslow Road, Manchester M20 9BX, United Kingdom

^‡To whom correspondence should be addressed. Tel.: 44-161-446-3129; Fax: 44-161-446-3109.

Abstract

Members of the Id family of helix-loop-helix proteins function as negative regulators of DNA binding, E protein, helix-loop-helix transcription factors in the control of cell growth, differentiation, and development. By using transient transfection analysis of COS cells, we show that in the absence of its E protein target, the Id3 protein is localized exclusively to the cytoplasm/perinuclear region. Co-transfection with E protein (E47) results in nuclear translocation of the Id3 protein, a process requiring both a functional Id helix-loop-helix dimerization domain and an E protein nuclear localization signal. Id3 that is associated with E protein displays an extended half-life, while the E protein itself is more rapidly turned over. These observations demonstrate that E protein, by nuclear chaperoning Id, can regulate the available cellular pool of its own inhibitory partner.

Footnotes

↵* This work was supported by the UK Cancer Research Campaign. 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:

bHLH

basic helix-loop-helix

DMEM

Dulbecco's modified Eagle's medium

HB

helix buffer

FITC

fluorescein isothiocyanate

TRITC

Texas Red isothiocyanate

NLS

nuclear localization sequence

TBS

Tris-buffered saline

DAPI

4-6 diamine-2-phenylindole

PCR

polymerase chain reaction.
↵²R. Deed, unpublished results.
- Received July 8, 1996.