POLYPYRIMIDINE TRACT-BINDING PROTEIN INTERACTS WITH HNRNP-L

Polypyrimidine tract-binding protein (PTB) is involved in pre-mRNA spl icing and internal ribosomal entry site (IRES)-dependent translation. In order to identify cellular protein(s) interacting with PTB, we perf ormed a yeast two-hybrid screening. Heterogeneous nuclear ribonucleopr otein L (hnRNP L) was identified as a PTB-binding protein. The interac tion between PTB and hnRNP L was confirmed in an in vitro binding assa y. Both PTB and hnRNP L were found to localize in the nucleoplasm, exc epting the nucleoli, in HeLa cells by the green fluorescent protein (G FP)-fused protein detection method. The N-terminal half of PTB (aa 1-3 29) and most of hnRNP L (aa 141-558) is required for the interaction b etween PTB and hnRNP L. (C) 1998 Federation of European Biochemical So cieties.