Molecular characterization of a novel fission yeast gene spUAP2 that interacts with the splicing factor spU2AF59

A protein essential for pre-mRNA splicing, the U2 auxiliary factor (U2AF), is composed of a large and small subunit. Previously we cloned and characterized both subunits. spU2AF(59) and spU2AF(23), from fission yeast. We now report a novel U2AF-associated-protein, spUAP2, which interacts with both subunits. SpUAP2 contains a classical and a degenerate RNA recognition motif (RRM), both of which are required for interaction with spU2AF(59) Interaction also requires the arginine/serine-rich region and the first RRM of spU2AF(59). A null allele of the gene for spUAP2 is lethal.