Soma-specific expression and cloning of PSI, a negative regulator of P element pre-mRNA splicing

Genes Dev. 1995 Feb 1;9(3):269-83. doi: 10.1101/gad.9.3.269.


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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alternative Splicing / genetics*
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cloning, Molecular
  • DNA, Complementary
  • Drosophila / genetics*
  • Drosophila Proteins*
  • Molecular Sequence Data
  • Nuclear Proteins*
  • RNA Precursors / genetics*
  • RNA, Messenger / genetics*
  • RNA-Binding Proteins / biosynthesis
  • RNA-Binding Proteins / genetics*
  • RNA-Binding Proteins / immunology
  • Recombinant Proteins / genetics
  • Recombinant Proteins / immunology
  • Repetitive Sequences, Nucleic Acid


  • DNA, Complementary
  • Drosophila Proteins
  • Nuclear Proteins
  • PSI protein, Drosophila
  • RNA Precursors
  • RNA, Messenger
  • RNA-Binding Proteins
  • Recombinant Proteins

Associated data

  • GENBANK/S75665
  • GENBANK/S75666