Correspondence between a mammalian spliceosome component and an essential yeast splicing factor.

None of the mammalian splicing factors that have been cloned corresponds to the yeast pre-messenger RNA splicing factors, the PRP proteins. Here, a generalizable strategy was used to isolate a complementary DNA encoding the mammalian spliceosome-associated protein (SAP) SAP 62. It is demonstrated that SAP 62 is the likely functional homolog of the yeast PRP11 protein. Both PRP11 and SAP 62 associate stably with the spliceosome, contain a single zinc finger, and display significant amino acid sequence similarity. Unlike PRP11, SAP 62 contains 22 proline-rich heptapeptide repeats at the carboxyl-terminus.