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° 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.