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Avian myeloblastosis virus and E26 virus oncogene products are nuclear proteins
Abstract:
The defective acute leukemia viruses avian myeloblastosis virus (AMV) and E26 virus each contain an inserted cellular sequence related to the same highly conserved cellular gene, proto-amv. The oncogenes of these two retroviruses differ from this cellular proto-oncogene in gene structure, transcript structure, and gene product. The product of the AMV oncogene (myb) is a 48,000 Mr protein, p48myb, encoded by a transduced segment (amv) of proto-amv flanked by short helper-virus-derived terminal sequences. The E26 virus oncogene product is a 135,000 Mr protein, p135gag-amve-ets, encoded by significant portions of a viral structural gene (gag), sequences related to proto-amv (amve), and additional E26-specific sequences (ets) transduced from cellular proto-ets. Both p48myb and p135gag-amve-ets transforming proteins are located in the nucleus of cells transformed by these viruses. A protein of 110,000 Mr which is specifically immunoprecipitated by antisera to amv peptides and may be the product of the normal cellular gene (proto-amv) has been located in the cytoplasm of cells that express proto-amv mRNA.
Insights
Avian myeloblastosis virus (AMV) and E26 virus oncogenes, derived from proto-amv, produce distinct nuclear transforming proteins (p48myb and p135gag-amve-ets). The normal proto-amv gene product (110,000 Mr) is found in the cytoplasm.
Area of Science:
- Molecular Biology
- Virology
- Oncogenesis
Background:
- Defective acute leukemia viruses, avian myeloblastosis virus (AMV) and E26 virus, harbor oncogenes originating from the conserved cellular gene, proto-amv.
- These viral oncogenes exhibit structural and functional differences compared to their cellular proto-oncogene counterpart.
Purpose of the Study:
- To characterize the oncogenes of AMV and E26 viruses and their encoded proteins.
- To investigate the cellular localization of viral oncoproteins and the normal proto-amv gene product.
Main Methods:
- Analysis of viral oncogene structure and transcript.
- Protein characterization using molecular weight (Mr) determination.
- Immunoprecipitation assays using antisera to viral peptides.
- Cellular localization studies via subcellular fractionation.
Main Results:
- The AMV oncogene (myb) encodes a 48,000 Mr nuclear protein (p48myb).
- The E26 virus oncogene encodes a 135,000 Mr nuclear protein (p135gag-amve-ets), incorporating gag, amve, and ets sequences.
- A 110,000 Mr protein, potentially the normal proto-amv product, was identified in the cytoplasm of expressing cells.
Conclusions:
- Viral oncogenes derived from proto-amv generate distinct transforming proteins with nuclear localization.
- The cellular proto-amv gene product resides in the cytoplasm, suggesting differential roles and regulation compared to viral oncoproteins.