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Shen-Ong, G L and Lüscher, B and Eisenman, R N (1989) . Molecular and cellular biology, 9 (12). pp. 5456-5463. ISSN 0270-7306

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The major protein encoded by the c-myb oncogene in many species has been identified as an unstable, nuclear DNA-binding protein with an apparent molecular mass of 75 to 80 kilodaltons (p75c-myb). Recently, an alternatively spliced form of c-myb-encoded mRNA has been identified in murine cells containing either normal or rearranged c-myb genes. This mRNA includes a new exon, termed E6A, formed through use of cryptic splice sites located in the large intron between c-myb exons vE6 and vE7. E6A is predicted to contribute an internal 121-residue in-frame insertion into a region C terminal of the DNA-binding domain the c-myb-encoded protein. Here we report the identification of an 85-kilodalton (p85c-myb-E6A) protein as the translation product of the alternatively spliced E6A c-myb mRNA. This protein as well as p75c-myb were precipitated with anti-Myb antibodies raised against the conserved DNA-binding region of c-Myb. Proteolytic mapping studies showed that the two proteins are highly related but not identical. However, only the p85 protein reacted with an antiserum prepared against the E6A region expressed in bacteria, demonstrating that p85 but not p75 contains E6A sequences. In addition, the mobilities of both p85 and p75 were increased in myeloid tumor cell lines containing proviral integrations upstream of the 5' coding exons of v-myb, indicating that both proteins are truncated forms of c-Myb expressed from the same disrupted allele. p75c-myb and p85c-myb-E6A were indistinguishable with respect to nuclear localization and protein half-life. Furthermore, both forms of Myb were synthesized continuously throughout the cell cycle in 70Z ore-B cells. The contribution of the E6A domain to c-myb function remains to be elucidated.

Item Type: Article or Abstract
Additional Information: This article is freely available in PubMed Central and at the journal's website.
PubMed ID: 2685565
PMCID: PMC363714
Grant Numbers: Post-doctoral grant 83.503.0.87, CA 28151
Keywords or MeSH Headings: Amino Acid Sequence; Animals; Antigen-Antibody Complex/analysis; Cell Line; Electrophoresis, Polyacrylamide Gel; Immune Sera; Lymphoma; Mice; Mice, Inbred Strains; Molecular Sequence Data; Molecular Weight; Oligopeptides/chemical synthesis; Protein Biosynthesis; Protein-Tyrosine Kinases/genetics; Proto-Oncogene Proteins/genetics/isolation & purification; Proto-Oncogene Proteins c-myb; Proto-Oncogenes; RNA Splicing; RNA, Messenger/genetics; T-Lymphocytes/metabolism;
Subjects: Molecules > RNA
Molecules > Proteins
Molecules > Genes > Oncogenes
Depositing User: Library Staff
Date Deposited: 03 Dec 2008 22:24
Last Modified: 21 May 2010 22:45

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