Corf, the Rev/Rex homologue of HTDV/HERV-K, encodes an arginine-rich nuclear localization signal that exerts a trans-dominant phenotype when mutated

Regulation of nucleo-cytoplasmic export of viral transcripts by a viral pro tein (Rev/Rex) is a characteristic feature in the replication cycle of comp lex retroviruses. We recently reported that the endogenous retrovirus famil y HTDV/HERV-K encodes a protein, Corf, that is a cellular Counterpart of Re v/Rex function and thus a new component of nucleo-cytoplasmic pathways. In HTDV/HERV-K-expressing cells, Corf is localized within the nucleoli. Here w e describe the nuclear localization signal (NLS) of the Corf protein. Mutat ions in the NLS lead to cytoplasmic accumulation of the mutated protein and abrogate Corf function in a trans-dominant way. (C) 2000 Academic Press.