Characterization of cDNAs encoding the polypyrimidine tract-binding protein

Anna Gil, Phillip A. Sharp, Sharon F. Jamison, Mariano A. Garcia-Blanco

Research output: Contribution to journalArticlepeer-review

221 Scopus citations


The polypyrimidine tract of mammalian introns is recognized by a 62-kD protein (pPTB). Mutations in the polypyrimidine tract that reduce the binding of pPTB also reduce the efficiency of formation of the pre-spliceosome complex containing U2 snRNP. The PTB protein was purified to homogeneity by affinity chromatography on a matrix containing poly(U), and peptide sequence was used to isolate several cDNAs. Because a variety of cell types express mRNA complementary to these cDNAs, PTB may be a ubiquitous splicing factor. Three classes of cDNAs were identified, on the basis of the presence of additional sequences at an internal position. This variation in sequence probably reflects alternative splicing of the PTB pre-mRNA and produces mRNAs encoding the prototype PTB protein, a form of PTB protein containing 19 additional residues, and a truncated form of PTB protein with a novel carboxyl terminus. A murine homolog of pPTB has been characterized previously as a DNA-binding protein. Sequence comparisons indicate that pPTB is distantly related to the hnRNP L protein and that these two proteins should be considered as members of a novel family of RNA-binding proteins.

Original languageEnglish (US)
Pages (from-to)1224-1236
Number of pages13
JournalGenes and Development
Issue number7
StatePublished - Jul 1991
Externally publishedYes


  • Polypyrimidine tract
  • Pre-spliceosome complex
  • RNA binding
  • Splicing
  • U2 snRNP

ASJC Scopus subject areas

  • Genetics
  • Developmental Biology


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