PROTEIN-PROTEIN INTERACTIONS AND 5'-SPLICE-SITE RECOGNITION IN MAMMALIAN MESSENGER-RNA PRECURSORS

Exactly how specific splice sites are recognized during the processing of complex precursor messenger RNAs is not clear. Small nuclear ribon ucleoprotein particles (snRNPs) are involved, but are not sufficient b y themselves to define splice sites. Now a human protein essential for splicing in vitro, called alternative splicing factor/splicing factor 2, is shown to cooperate with the U1 snRNP particle in binding pre-mR NA. This cooperation is probably achieved by specific interactions bet ween the arginine/serine-rich domain of the splicing factor and a simi lar region in a U1 snRNP-specific protein.