Functional aspects of B-Myb in early Xenopus development

T Bouwmeester, I van Wijk, D Wedlich, T Pieler

Research output: Contribution to journalArticleAcademicpeer-review


The gene encoding Xenopus B-Myb (XB-Myb), a protein structurally related to the nuclear protooncogene product c-Myb, is expressed in early Xenopus embryogenesis. We report on developmental alterations in the nucleocytoplasmic distribution and phosphorylation of XB-Myb in Xenopus oocytes and embryos, as well as on a negative regulatory role of the carboxyl terminus in sequence specific DNA binding. In growing oocytes and early embryonic stages the protein is primarily located in the nucleus; in the full-grown oocyte, however, it remains sequestered in the cytoplasmic compartment. Upon meiotic maturation of the oocyte, XB-Myb becomes hyperphosphorylated. Oocyte/egg isolates of XB-Myb are inhibited in their specific DNA binding activity; truncation of the carboxyl terminal region relieves this block in nucleic acid recognition. Furthermore, we have used overexpression of XB-Myb in Xenopus embryos by means of mRNA injection as an assay for gene function in vivo. Overexpression of full-length XB-Myb, not of the carboxyl terminal deletion mutant, results in an altered morphology of lateral plate mesoderm.

Original languageEnglish
Pages (from-to)1029-38
Number of pages10
Issue number4
Publication statusPublished - Apr 1994


  • Animals
  • Blotting, Western
  • Cell Cycle Proteins
  • Cell Nucleus/metabolism
  • Consensus Sequence
  • Cytoplasm/metabolism
  • DNA-Binding Proteins/metabolism
  • DNA/metabolism
  • Embryo, Nonmammalian/metabolism
  • Genes, myc
  • Immunohistochemistry
  • In Situ Hybridization
  • Meiosis
  • Oocytes/metabolism
  • Phosphorylation
  • Proto-Oncogene Proteins c-myc/metabolism
  • RNA Processing, Post-Transcriptional
  • Trans-Activators
  • Transcription Factors/metabolism
  • Xenopus/embryology

Cite this