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

Nuclear factor I (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 (NL Ss) are still unknown in all NF1s, We hale identified two NLSs in NF1-A, an d both are required for full translocation to the nucleus, although one of them itself has a partial translocation ability. These two NLSs are conserv ed 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 c onstruct homodimer and heterodimer, these findings indicate the differentia l regulations of the NF1 translocation. (C) 2000 Federation of European Bio chemical Societies. Published by Elsevier Science B.V. All rights reserved.