Differential expression of two Xenopus c-myc proto-oncogenes during development.
AUTOR(ES)
Vriz, S
RESUMO
Two distinct Xenopus c-myc cDNA clones have been characterized from an oocyte cDNA library. This allowed a comparison of the c-myc protein sequence across the vertebrate phylum to be made and prominent conservations to be identified. The majority of the sequence differences between the two Xenopus c-myc cDNAs are in the 5' and 3' untranslated regions. Sequence-specific oligonucleotide probes from the 5' untranslated region were used to demonstrate the differential expression of the two c-myc mRNAs during development. One of the mRNAs corresponds to the Xenopus c-myc gene previously reported expressed as a stable maternal mRNA uncoupled from cell division during oogenesis (c-myc I). It is the major mRNA species expressed during oogenesis and is expressed again from the zygotic genome in post-gastrula embryos. In contrast, the second c-myc mRNA (c-myc II) is expressed only from the maternal genome during oogenesis. Primer extension experiments show that in the oocyte the transcriptional initiation sites for c-myc I and c-myc II are at different distances from the translational start site. The 'oocyte-specific' and 'somatic-type' developmental regulation of c-myc is reminiscent of polymerase III 5S RNA gene expression in Xenopus, and may provide new insights into the developmental regulation of genes transcribed by RNA polymerase II.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=401586Documentos Relacionados
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