Many eukaryotic genes are interrupted by intervening sequences which are excised from mRNA precursors (pre-mRNAs) during pre mRNA splicing. The long-term objective of our research is to understand how pre-mRNA splice sites are accurately and efficiently recognized, cleaved and ligated during splicing. Recognition and cleavage of 5' splice sites is mediated by U1 small nuclear ribonucleoprotein, a sub-assembly of the spliceosome. The approach has been to first characterize the structure and function of U1 snRNP and have shown that the U1 snRNP-specific U1-70K and U1-A proteins are sequence-specific RNA-binding protein. Elucidating the functions of the various components of U1 snRNP during pre-mRNA splicing is being planned. This will involve extending the studies of U1 snRNP structure, determining the mechanism(s) of sequence- specific RNA-binding by the U1-70K and U1-A proteins, and defining the properties of various components of U1 snRNP. As members of the RNP sequence domain class of RNA-binding proteins, the U1-70K, U1-A, and U2-B" proteins will also be used as models to study this class of sequence-specific RNA-protein interactions. The functions of these snRNP proteins during pre-mRNA splicing may be modulated, through regulation of the biosynthesis of the human U1-70K snRNP protein, via alternative splicing of its own pre-mRNA will be studied.
