title: Soma-specific expression and cloning of PSI, a negative regulator of P element pre-mRNA splicing.
abstract: PSI is an RNA-binding protein involved in repressing splicing of the P element third intron in Drosophila somatic cell extracts. PSI produced in bacteria restores splicing inhibition to an extract relieved of inhibitory activity, indicating that PSI plays a direct role in somatic inhibition. Sequence analysis of cDNAs encoding PSI reveals three KH RNA-binding domains, a conserved motif also found in the yeast splicing regulator MER1. Notably, PSI is expressed highly in somatic embryonic nuclei but is undetectable in germ-line cells. In contrast, hrp48, another protein implicated in somatic inhibition, is found in the nucleus and cytoplasm of both tissues. The splicing inhibitory properties and soma-specific expression of PSI may be sufficient to explain the germ-line-specific transposition of P elements.
authors.affiliation: Department of Molecular and Cell Biology, University of California at Berkeley 94720.
authors.forename: C W
authors.initials: CW
authors.lastname: Siebel
authors.forename: A
authors.initials: A
authors.lastname: Admon
authors.forename: D C
authors.initials: DC
authors.lastname: Rio
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D012322:RNA Precursors / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D018076:DNA, Complementary; D029721:Drosophila Proteins; D009687:Nuclear Proteins; C092281:PSI protein, Drosophila; D012322:RNA Precursors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins