Phosphorylation of specific sites in the gag-myc polyproteins encoded by MC29-type viruses correlates with their transforming ability.

Ramsay, Gary; Hayman, Michael J.; Bister, Klaus

doi:10.1002/j.1460-2075.1982.tb01305.x

Cited by 48 publications

(26 citation statements)

References 24 publications

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“…Histones are the only other nuclear protein whose phosphorylation has been reported to be stimulated by TPA (2,38). However, a number of other nuclear oncogene proteins like mVc (14,40), nvyb (W. Boyle and T. Hunter, personal communication), p53 cellular tumor antigen (53), simian virus 40 large T antigen (53), polyomavirus large T antigen (15), and adenovirus EIA (50) tryptic peptides could be generated (Fig. 8).…”

Section: Methodsmentioning

confidence: 99%

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Modification of fos proteins: phosphorylation of c-fos, but not v-fos, is stimulated by 12-tetradecanoyl-phorbol-13-acetate and serum.

Barber¹,

Verma²

1987

Mol. Cell. Biol.

176

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We have investigated the covalent modification of the proteins encoded by the murine fos proto-oncogene (c-fos) and that of the corresponding gene product of FBJ murine osteosarcoma virus (v-fos). Both proteins are posttranslationally processed in the cell, resulting in forms with lower electrophoretic mobilities than that of the initial translation product on sodium dodecyl sulfate-polyacrylamide gels. Treatment with alkaline phosphatase indicates that most, if not all, of this electrophoretic shift is due to phosphoesterification of both proteins. These phosphoryl groups stoichiometrically modify the v-fos and c-fos proteins on serine residues and turn over rapidly in vivo in the presence of protein kinase inhibitors (half-life, < 15 min [32P]phosphate-labeled proteins indicates that although the two proteins have several tryptic phosphopeptides in common, the c-fos protein contains unique major tryptic phosphopeptides that the v-fos protein lacks. These unique sites of c-fos phosphorylation have been tentatively localized to the carboxy-terminal 20 amino acid residues of the protein. Phosphorylation of the c-fos protein, but not the v-fos protein, can be stimulated at least fivefold in vivo by the addition of either 12-tetradecanoyl-phorbol-13-acetate or serum. This increase in the steady-state degree of phosphorylation of c-fos appears to be independent of protein kinase C since phosphorylation is Ca2+ and diacylglycerol independent. The possible role of phosphorylation of these proteins in cellular transformation is discussed.

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Section: Methodsmentioning

confidence: 99%

“…This raises the possibility that the proteins may lead to transcriptional trans-activation by directly binding to specific DNA sequences. It is possible that phosphorylation regulates the affinity of these proteins for specific DNA sequences as has been proposed for simian virus 40 large T antigen (49).…”

Section: Methodsmentioning

confidence: 99%

Modification of fos proteins: phosphorylation of c-fos, but not v-fos, is stimulated by 12-tetradecanoyl-phorbol-13-acetate and serum.

Barber¹,

Verma²

1987

Mol. Cell. Biol.

176

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“…Immunoprecipitation from labeled cell lysates was performed as described previously (36 (36). For competitive inhibition of antibody precipitation (blocking) experiments, 20 ,ug of peptide per ,ul of sera were incubated together for 30 min at 4°C and then used directly in the immunoprecipitation assay.…”

Section: Methodsmentioning

confidence: 99%

“…For competitive inhibition of antibody precipitation (blocking) experiments, 20 ,ug of peptide per ,ul of sera were incubated together for 30 min at 4°C and then used directly in the immunoprecipitation assay. The released proteins were electrophoresed on discontinuous 10% SDS-polyacrylamide gels and fluorographed (36).…”

Section: Methodsmentioning

confidence: 99%

Human proto-oncogene N-myc encodes nuclear proteins that bind DNA.

et al. 1986

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N-myc is a gene whose amplification has been implicated in the genesis of several malignant human tumors. We have identified two proteins with molecular weights of 65,000 and 67,000 encoded by N-myc. The abundance of these proteins in tumor cells was consonant with the extent of amplification of N-myc. The two proteins apparently arose from the same mRNA, were phosphorylated, were exceptionally unstable, were located in the nucleus of cells, and bound to both single- and double-stranded DNA. These properties suggest that the products of N-myc and of the related proto-oncogene c-myc may have similar biochemical functions and that N-myc may be a regulatory gene. Our findings sustain the view that inordinate expression of N-myc may contribute to the genesis of several different human tumors.

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“…In quail cells transformed by MC29 virus, a viral fusion protein 110 kDa gag-myc is synthesized [18]. In order to confirm that the 70 kDa protein is related to the viral myc protein, we have tested the anti-70 kDa antiserum by Western blot analysis using extracts of quail cells transformed by MC29 virus.…”

Section: Polyclonal Antiserum Against the 70 Kda Proteinmentioning

confidence: 99%

A protein of Halobacterium halobium immunologically related to the v‐myc gene product

et al. 1988

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A 70 kDa protein of H&bacterium halobium cross-reacts with an antiserum directed against the v-myc gene product of the avian myelocytomatosis virus (MC29). This cross-reaction is in agreement with hybridization studies which indicate that H. halobium possesses DNA and RNA sequences homologous to the v-myc gene.v-myc gene product; gag-myc protein; c-myc protein; Southern blot; Western blot analysis; (Archaebacteria)

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Phosphorylation of specific sites in the gag-myc polyproteins encoded by MC29-type viruses correlates with their transforming ability.

Cited by 48 publications

References 24 publications

Modification of fos proteins: phosphorylation of c-fos, but not v-fos, is stimulated by 12-tetradecanoyl-phorbol-13-acetate and serum.

Modification of fos proteins: phosphorylation of c-fos, but not v-fos, is stimulated by 12-tetradecanoyl-phorbol-13-acetate and serum.

Human proto-oncogene N-myc encodes nuclear proteins that bind DNA.

A protein of Halobacterium halobium immunologically related to the v‐myc gene product

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