U2AF HOMOLOG REQUIRED FOR SPLICING IN-VIVO

Several fission yeast temperature-sensitive mutants defective in pre-m RNA processing (prp- mutants) at the nonpermissive temperature have be en identified. Here, the prp2+ gene has been cloned by its ability to complement the temperature-sensitive growth defect of a prp2- mutant. The gene also corrects the pre-mRNA splicing defect of prp2- mutants a nd encodes a 59-kilodalton polypeptide (PRP2). A molecular characteriz ation indicates that PRP2 is a previously uncharacterized yeast splici ng factor with extensive similarity to the mammalian splicing factor U 2AF65. Thus, this study provides evidence that a U2AF homolog particip ates in RNA processing in vivo.