Structure and subcellular localization of a small RNA-binding protein from tobacco.

In this study, a cDNA encoding a small RNA-binding protein was isolated from a Nicotiana sylvestris cDNA library. The predicted protein (RGP-3) is 144 amino acid residues long, and contains a consensus sequence-type RNA binding domain (CS-RBD) of 83 amino acids and a short glycine-rich region of 15 amino acids. RGP-3 synthesized in Escherichia coli has high affinity for poly(U). Immunocytochemical analysis indicated that RGP-3 is localized in the nucleoplasm, and that RGP-1b, a related protein reported previously, is localized in the nucleolus. Possible roles of these proteins in pre-mRNA or pre-rRNA processing are discussed.