Molecular Characterization of the NelF2Bβ Gene Encoding a Putative elF2B β-Subunit in Nicotiana tabacum

The NeIF2Bβ cDNA encoding β-subunit of the translation initiation factor 2B (eIF2B-β) was identified from Nicotiana tabacum through protein interaction with PRK1, a reproductive-organ-specific receptor-like kinase (Park et al., 2000). The eIF2B is a guanine nucleotide-exchange protein that consists of five subunits, which function in the regulation of translation in eukaryotic cells. The NeIF2Bβ that shows a high homology in the amino acid sequence with other β-subunits also exhibits sequence similarity to a and δ subunits of eIF2B from yeast and animals. The NeIF2Bβ gene was expressed in all of the tissues examined, but the mRNA level was higher in reproductive tissues than in vegetative tissues. During anther development, the NeIF2Bβ mRNA was detected in all stages with a slightly higher level in the earliest stage. The NeIF2Bβ-GFP fusion protein was mainly localized in the cytosol.