In this study, a cDNA encoding a small RNA-binding protein was isolate
d 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 glycin
e-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-lb, a related
protein reported previously, is localized in the nucleolus. Possible
roles of these proteins in pre-mRNA or pre-rRNA processing are discuss
ed.