In cukaryotes, nuclear proteins that are transported into nuclei have nuclear localization signals (NLSs), which are recognized by proteins called importin alpha. We isolated a rice cDNA, #61L, and the corresponding gene that encodes a protein, which shows significant homology to the importin alpha. Although the encoded protein had only 23-27% amino acid identity to the importin alpha s from various organisms including plants, the fusion protein,vith glutathione S-transferase showed a specific binding activity to the NLS of SV40 T-antigen, These results suggest that the rice #61L protein is a novel importin alpha in plants. (C) 1998 Federation of European Biochemical Societies.