Joan A. Steitz

Small RNA-protein complexes (RNPS) are ubiquitous in eukaryotic cells and inhabit specific cellular compartments. The most famous small nuclear RNPs (snRNPs) participate in pre-mRNA splicing by recognizing important intron signals and assembling to form an active splicing complex called a spliceosome. Several lower abundance snRNPs, which are related to the splicing snRNPs and act in either the excision of a rare, divergent class of introns or in other nuclear pre-mRNA processing events, are also being analyzed. The nucleolus possesses a distinct family of related snRNPs. We are investigating their functions in pre-ribosomal RNA processing, as well as their unusual mode of biogenesis. Finally, we are studying viral snRNPs, found in cells infected by some mammalian Herpes viruses.