Avian sarcoma virus UR2 encodes a transforming protein which is associated with a unique protein kinase activity
- 31 March 1982
- journal article
- research article
- Published by American Society for Microbiology in Journal of Virology
- Vol. 42 (1), 228-236
- https://doi.org/10.1128/jvi.42.1.228-236.1982
Abstract
UR2 is a newly characterized avian sarcoma virus whose genome contains a unique sequence that is not related to the sequences of other avian sarcoma virus transforming genes thus far identified. This unique sequence, termed ros, is fused to part of the viral gag gene. The product of the fused gag-ros gene of UR2 is a protein of 68,000 daltons (P68) immunoprecipitable by antiserum against viral gag proteins. In vitro translation of viral RNA and in vivo pulse-chase experiments showed that P68 is not synthesized as a larger precursor and that it is the only protein product encoded in the UR2 genome, suggesting that it is involved in cell transformation by UR2. In vivo, P68 was phosphorylated at both serine and tyrosine residues. Immunoprecipitates of P68 with anti-gag antisera had a cyclic nucleotide-independent protein kinase activity that phosphorylated P68, rabbit IgG in the immune complex and .alpha.-casein. The phosphorylation by P68 was specific to tyrosine of the substrate proteins. P68 was phosphorylated in vitro at only 1 tyrosine site, and the tryptic phosphopeptide of in vitro-labeled P68 was different from those of Fujinami sarcoma virus P140 and avian sarcoma virus Y73-P90. A comparison of the protein kinases encoded by UR2, Rous sarcoma virus, Fujinami sarcoma virus and avian sarcoma virus Y73 revealed that UR2-P68 protein kinase is distinct from the protein kinases encoded by those viruses by several criteria. Several different protein kinases encoded by viral transforming genes apparently have the same functional specificity and cause essentially the same cellular alterations.This publication has 38 references indexed in Scilit:
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