Distinct Regions Specify the Targeting of Otefin to the Nucleoplasmic Side of the Nuclear Envelope

doi:10.1074/jbc.272.4.2493

Distinct Regions Specify the Targeting of Otefin to the Nucleoplasmic Side of the Nuclear Envelope*

From the ^‡ Department of Genetics, Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904 and the
^§ Department of Electronics, Jerusalem College of Technology, Jerusalem 91160, Israel

^¶ To whom correspondence should be addressed. Tel.: 972-2-6585995; Fax: 972-2-5633066; E-mail: GRU{at}vms.huji.ac.il

Abstract

Otefin is a 45-kDa nuclear envelope protein with no apparent homology to other known proteins. It includes a large hydrophilic domain, a single carboxyl-terminal hydrophobic sequence of 17 amino acids, and a high content of serine and threonine residues. Cytological labeling located otefin on the nucleoplasmic side of the nuclear envelope. Chemical extraction of nuclei from Drosophila embryos revealed that otefin is a peripheral protein whose association with the nuclear envelope is stronger than that of lamin. Deletion mutants of otefin were expressed in order to identify regions that direct otefin to the nuclear envelope. These experiments revealed that the hydrophobic sequence at the carboxyl terminus is essential for correct targeting to the nuclear envelope, whereas additional regions in the hydrophilic domain of otefin are required for its efficient targeting and stabilization in the nuclear envelope.

Footnotes

↵* This work was supported by grants from the Israel-United States Binational Fund (BSF) by the Israel Academy of Sciences, and by the Council of Tobacco Research, United States of America. 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:

LAP

lamina-associated protein

LBR

lamin B receptor

NLS

nuclear localization signal of the glucocorticoid receptor (residues 497-524)

mAb

monoclonal antibody

FCS

fetal calf serum

PBS

phosphate-buffered saline

TBS

Tris-buffered saline

TPCK

N-tosyl-L-phenylalanine chloromethyl ketone.
- Received May 30, 1996.
- Revision received November 6, 1996.