Abstract
In E.coli and nitrogen-fixing bacteria, the availability of nitrogen within the cell is sensed as the glutamine by the GlnD. Total six genes for GlnD homologues were isolated from rice. The rice GlnD homologues are consisted of ACT domain repeats (ACR). The ACT domain, which was named after Aspartate kinase, Chorismate mutase, and TyrA, function as the amino acids binding domains. The OsACR is expected to be a Gln sensor, although the precise function is not yet known.
In addition to the previously isolated two GlnD homologues (OsACR3 and OsACR4) in rice, we have isolated another three genes (OsACR2, 5, 6). RT-PCR showed that expression pattern of each OsACR in rice leaves was different at various growth stage. Particularly, large accumulation of the OsACR3 mRNA was mainly detected in young leaves. Immunochemical and the promoter : GFP transient analysis indicated that OsACR3 protein was localized in the nucleus.
