1. Anti-Importin  3 NIH3T3 cells Primary hippocampal neurons Mouse ES cells Anti-Importin  1 Anti-Importin  1 NIH3T3 cells Primary hippocampal neurons Mouse ES cells NIH3T3 cells Primary hippocampal neurons Mouse ES cells Anti-E47 NIH3T3 cells Primary hippocampal neurons Mouse ES cells A B C D Supplementary figure 1 NIH3T3 cells Primary hippocampal neurons Mouse ES cells E Anti-NeuroD1 * * * * * Anti-GAPDH NIH3T3 cells Primary hippocampal neurons Mouse ES cells F

2. Flag-NeuroD1 Flag-  134-161 Anti-flagDAPI Supplementary figure 2

3. GFPInjection Marker NeuroD1-GFP NeuroD1-GFP + RanQ69L-GTP HeLa A B CD Supplementary figure 3 NIH3T3 EF HG GFPInjection Marker

4. Supplementary figure 4 Anti-RanBP5Anti-RanBP7 NeuroD1-GST +cytosol NeuroD1-GST +cytosol +RanQ69L － GTP Hela cell lysate GST beads+Cytosol NeuroD1-GST +cytosol NeuroD1-GST +cytosol +RanQ69L － GTP Hela cell lysate GST beads+Cytosol 75 100 150 A B

5. Supplementary figure 5 Importin  1 Importin  +  1 (NeuroD1)

6. (A) Database : NCBInr 20100904 (11744690 sequences; 4010973687 residues) Taxonomy : Homo sapiens (human) (232987 sequences) Timestamp : 8 Sep 2010 at 09:45:05 GMT Top Score : 182 for gi|19923142, importin subunit beta-1 [Homo sapiens] Mascot Score Histogram Protein score is -10*Log(P), where P is the probability that the observed match is a random event. Protein scores greater than 66 are significant (p<0.05) Search Parameters Enzyme : Trypsin Fixed modifications : Carbamidomethyl (C) Variable modifications : Oxidation (M) Mass values : Monoisotopic Protein Mass : 95 kDa Peptide Mass Tolerance : ± 0.2 Da Peptide Charge State : 1+ Max Missed Cleavages : 1 Number of queries : 36 (B) Supplementary figure 6