Two nuclear localization signals are required for nuclear translocation of nuclear factor 1-A

Nuclear factor 1 (NF1) proteins are encoded by at least four genes (NF1-A, B, C, X). Although DNA-binding and the transcription regulation domains of these proteins are well characterized, the nuclear localization signals (NLSs) are still unknown in all NF1s. We have identified two NLSs in NF1-A, and both are required for full translocation to the nucleus, although one of them itself has a partial translocation ability. These two NLSs are conserved in all four NF1s. Interestingly, three isoforms of NF1-A (NF1-A1, A2, A4) have two NLSs and translocate completely to the nucleus. In contrast, NF1-A3 lacks the second NLS and partially stays in the cytoplasm. Since NF1s construct homodimer and heterodimer, these findings indicate the differential regulations of the NF1 translocation. Copyright (C) 2000 Federation of European Biochemical Societies.