The Pax-5 gene is alternatively spliced during B-cell development

Patty Zwollo, Hector Arrieta, Kaleo Ede, Karen Molinder, Stephen Desiderio, Roberta Pollock

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


The transcription factor Pax-5 is expressed during the early stages of B-cell differentiation and influences the expression of several B-cell- specific genes. In addition to the existing isoform (Pax-5, which we have named Pax-5a), we have isolated three new isoforms, Pax-5b, Pax-5d, and Pax- 5e, from murine spleen and B-lymphoid cell lines using library screenings and polymerase chain reaction amplification. Isoforms Pax-5b and Pax-5e have spliced out their second exon, resulting in proteins with only a partial DNA- binding domain. Isoforms Pax-5d and Pax-5e have deleted the 3'-region, which encodes the transactivating domain, and replaced it with a novel sequence. The existence of alternative Pax-5 transcripts was confirmed using RNase protection assays. Furthermore, Pax-5a and Pax-5b proteins were detected using Western blot analysis. Pax-5a was detectable in pro-, pre-, and mature B-cell lines, but not in two plasmacytomas; Pax-5b was shown to be present at low levels in mature B-cell lines and, unexpectedly, in one plasma cell line, but not in pro-B-cell or T-cell lines. Mobility shift assays showed that in vitro translated Pax-5a and Pax-5d, but not Pax-5b or Pax-5e, could interact with a B-cell-specific activator protein-binding site on the blk promoter. Using this assay, we also showed that Pax-5d was present in nuclear extracts of some (but not all) B-lymphoid lines and interacts with the B-cell-specific activator protein-binding site. The pattern of differential expression of alternatively spliced Pax-5 isoforms suggests that they may be important regulators of transcription during B-cell maturation.

Original languageEnglish (US)
Pages (from-to)10160-10168
Number of pages9
JournalJournal of Biological Chemistry
Issue number15
StatePublished - Apr 11 1997

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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