Cloning and intracellular localization of the U2 small nuclear ribonucleoprotein auxiliary factor small subunit

M. Zhang, P. D. Zamore, M. Carmo-Fonseca, A. I. Lamond, M. R. Green

Research output: Contribution to journalArticle

161 Citations (Scopus)


U2 small nuclear ribonucleoprotein auxiliary factor (U2AF), an essential mammalian splicing factor, is composed of two subunits: a 65-kDa protein (U2AF65), which binds the pre-mRNA polypyrimidine tract and is required for in vitro splicing, and an associated 35-kDa protein (U2AF35). Here we report the isolation of a cDNA encoding U2AF35. U2AF35 contains sequence motifs found in several mammalian pre-mRNA splicing factors. We show directly that U2AF65 and U2AF35 interact with each other and delineate the regions of both proteins that mediate this interaction. Using anti-peptide antibodies against U2AF35, we show that the protein has the intracellular distribution characteristic of U2AF65. Both U2AF65 and U2AF35 are concentrated in a small number of nuclear foci corresponding to coiled bodies, subnuclear organelles first identified by light microscopy in 1903.

Original languageEnglish
Pages (from-to)8769-8773
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number18
Publication statusPublished - 15 Sep 1992



  • arginine, serine rich
  • coiled body
  • RNA binding
  • spliceosome
  • splicing

Cite this