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HCF‐dependent nuclear import of VP16
Author(s) -
Boissière Sylvie La,
Hughes Thomas,
O'Hare Peter
Publication year - 1999
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/18.2.480
Subject(s) - marie curie , curie , chart , library science , curie temperature , computer science , mathematics , physics , condensed matter physics , statistics , european union , ferromagnetism , business , economic policy
Transactivation by VP16 requires the formation of a multicomponent complex, the TAATGAAAT recognition factor complex (TRF.C), that contains in addition to VP16, two cellular proteins, Oct‐1 and HCF. HCF binds directly to VP16 and this promotes subsequent interaction of the VP16–HCF complex with the POU DNA‐binding domain of Oct‐1 and selective assembly onto target sites. Here we demonstrate a novel role of HCF in the intracellular compartmentalization of VP16. We show that while VP16 does not contain a consensus nuclear localization signal (NLS) and is largely cytoplasmic, co‐expression with HCF resulted in VP16 nuclear accumulation. A candidate NLS within the C‐terminus of HCF was identified and insertion of this motif into green fluorescent protein (GFP) promoted nuclear accumulation. Conversely, removal of this signal from HCF (HCFΔNLS) resulted in its cytoplasmic accumulation. Co‐expression of HCFΔNLS with wild‐type (wt) VP16, or of wt HCF with VP16 mutants lacking HCF‐binding activity failed to promote the nuclear enrichment of VP16. These results indicate that in addition to its role in stabilizing TRF.C, HCF acts as a nuclear import factor for VP16.