CLONING OF A CDNA-ENCODING AN IMPORTIN-ALPHA AND DOWN-REGULATION OF THE GENE BY LIGHT IN RICE LEAVES

The import of nuclear proteins into nuclei begins with recognition of nuclear localization signal-harboring proteins and binding to a nuclea r pore targeting complex. A cDNA for an importin-alpha protein, a subu nit of the complex, was isolated from rice plants. The amino acid sequ ence deduced from the nucleotide sequence of the cDNA exhibited a high homology to those of importin-alpha proteins from many organisms such as Arabidopsis thaliana, Saccharomyces cerevisiae, human, mouse, Xeno pus laevis and Drosophila melanogaster. Down-regulation of the transcr iption by light was shown in the leaves of light- and dark-grown seedl ings by RNA blot analysis. The down-regulation was specific to leaves, whereas no light effect was observed in root tissues or calli, in whi ch higher levels of the transcript were detected. (C) 1998 Elsevier Sc ience B.V. All rights reserved.