Human hnRNP L shuttles between nucleus and cytoplasm

The heterogeneous nuclear ribonucleoprotein L (hnRNP L) is an abundant nuclear protein and one of the major pre-mRNA binding proteins. It is a 68kD protein and contains 558 amino acid residues and four loosely conserved RNP-concensus RNA-binding domains. Recently published data suggest that hnRNP L plays roles on cytoplasmic functions, such as mRNA turnover and regulation of translation. In this study, we investigated the nucleo-cytoplasmic shuttling activity of hnRNP L using transient transfection in conjunction with interspecies heterokaryon assays. Here, we report that hnRNP L; although it is localized primarily in the nucleoplasm, shuttles between nucleus and cytoplasm. The hnRNP L protein is detected mainly in the nucleoplasm by immunofluorescence microscopy, presumably because the return of hnRNP L to the nucleus is very rapid.X116sciescopu