A member of the Ran-binding protein family, Yrb2p, is involved in nuclear protein export

A member of the Ran-binding protein family, Yrb2p, is involved in nuclear protein export

Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School and The Dana–Farber Cancer Institute, 44 Binney Street, Boston, MA 02115

Communicated by David M. Livingston, Dana–Farber Cancer Institute, Boston, MA (received for review February 18, 1998)

Abstract

Yeast cells mutated in YRB2, which encodes a nuclear protein with similarity to other Ran-binding proteins, fail to export nuclear export signal (NES)-containing proteins including HIV Rev out of the nucleus. Unlike Xpo1p/Crm1p/exportin, an NES receptor, Yrb2p does not shuttle between the nucleus and the cytoplasm but instead remains inside the nucleus. However, by both biochemical and genetic criteria, Yrb2p interacts with Xpo1p and not with other members of the importin/karyopherin β superfamily. Moreover, the Yrb2p region containing nucleoporin-like FG repeats is important for NES-mediated protein export. Taken together, these data suggest that Yrb2p acts inside the nucleus to mediate the action of Xpo1p in at least one of several nuclear export pathways.

Footnotes

↵ * To whom reprint requests should be addressed at: The Dana–Farber Cancer Institute, Smith Building, Room 922, 44 Binney Street, Boston, MA 02115. e-mail: pamela_silver{at}dfci.harvard.edu.
ABBREVIATIONS:

NLS,

nuclear localization sequence;

NES,

nuclear export signal;

NPC,

nuclear pore complex;

GFP,

green fluorescent protein