Cytosolic proteins that specifically bind nuclear location signals are receptors for nuclear import

Stephen A. Adam*, Larry Geracet

*Corresponding author for this work

Research output: Contribution to journalArticle

311 Scopus citations

Abstract

We have purified two major polypeptides of 54 and 56 kd from bovine erythrocytes that specifically bind the nuclear location sequence (NLS) of the SV40 large T antigen. When added to a permeabilized cell system for nuclear import, the purified proteins increase by 2- to 3-fold the nuclear accumulation of a fluorescent protein containing the large T antigen NLS. The import stimulation is saturable and dependent upon the presence of cytosol. Nuclear protein accumulation in vitro is sensitive to inactivation by N-ethylmaleimide (NEM). NEM inactivation can be overcome by addition of the purified NLS-binding proteins to the import system. NEM treatment of the purified proteins abolishes their ability to stimulate import but does not affect NLS binding. Our results indicate that the NLS-binding proteins are NEM-sensitive receptors for nuclear import. At least one other NEM-sensitive cytosolic activity and an NEM-insensitive cytosolic activity are also necessary for protein import in vitro.

Original languageEnglish (US)
Pages (from-to)837-847
Number of pages11
JournalCell
Volume66
Issue number5
DOIs
StatePublished - Sep 6 1991

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

Fingerprint Dive into the research topics of 'Cytosolic proteins that specifically bind nuclear location signals are receptors for nuclear import'. Together they form a unique fingerprint.

Cite this