Regulation of pp60c-src and its interaction with polyomavirus middle T antigen in insect cells.
High yields of soluble, biologically active pp60c-src and middle t antigen (MTAg) of polyomavirus were produced in insect cells, using a baculovirus expression system. In mammalian cells, pp60c-src undergoes a regulatory phosphorylation on Tyr-527 in vivo and is autophosphorylated on Tyr-416 in vitro. In insect cells, pp60c-src was phosphorylated primarily on Tyr-416, although Tyr-527 was detectable at a low level. A kinase-negative mutant of pp60c-src was not phosphorylated on either Tyr-527 or Tyr-416 in insect cells and thus is an excellent biochemical reagent to search for the regulatory kinase that usually phosphorylates Tyr-527 in mammalian cells. MTAg synthesized in insect cells was not phosphorylated on tyrosine residues in vivo or in vitro, suggesting that it did not associate with any endogenous tyrosine kinases. However, MTAg isolated from cells coinfected with viruses encoding both MTAg and pp60c-src was phosphorylated on tyrosine residues both in vivo and in vitro.
Piwnica-Worms
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Dana-Farber Cancer Institute, Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115.
Williams
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NG
Cheng
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Roberts
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TM
D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000096:biosynthesis / Q000235:genetics*; D002460:Cell Line; D015967:Gene Expression Regulation, Viral; D005814:Genes, Viral; D005822:Genetic Vectors; D007304:Insect Viruses / Q000235:genetics*; D007313:Insecta; D008715:Methionine / Q000378:metabolism; D019814:Myristic Acid; D009227:Myristic Acids / Q000378:metabolism; D015688:Oncogene Protein pp60(v-src) / Q000096:biosynthesis / Q000235:genetics*; D010449:Peptide Mapping; D010748:Phosphopeptides / Q000302:isolation & purification; D010766:Phosphorylation; D011120:Polyomavirus / Q000235:genetics*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D015678:Viral Structural Proteins / Q000235:genetics*
D000952:Antigens, Polyomavirus Transforming; D009227:Myristic Acids; D010748:Phosphopeptides; D015678:Viral Structural Proteins; D019814:Myristic Acid; D008715:Methionine; D011494:Protein Kinases; D015688:Oncogene Protein pp60(v-src)