Low-temperature-dependent expression of a rice gene encoding a protein with a leucine-zipper motif.

We have isolated from rice suspension cells three non-sequence-related cDNAs the expression of which is markedly induced by low, non-freezing temperature. Here we further characterize one of the cDNA clones, lip19. Expression of lip19 is positively regulated by low temperature, but not affected by high (40 degrees C) temperature. Sequencing and primer extension analyses showed that lip19 has a long (552 bp) 5' non-coding sequence followed by a single open reading frame specifying a protein of 148 amino acids. The deduced amino acid sequence of the protein, Lip19, shows at its amino-terminus a conserved basic region followed by a "leucine-zipper" domain. The reported sequence most similar to Lip19 is maize OCSBF-1, which is a bZip-type DNA binding protein. The possibility is suggested that Lip19 is a transcriptional factor that is positively controlled by low temperature.