Role of the mitogenic property and kinase activity of p60src in tumor formation by Rous sarcoma virus.

Four temperature-sensitive (ts) Rous sarcoma virus src gene mutants with lesions in different parts of the gene represent three classes of alteration in pp60src. These classes are composed of mutants with (i) heat-labile protein kinase activities both in vitro and in vivo (tsLA27 and tsLA29), (ii) heat-labile kinases in vivo but not in vitro (tsLA33), and (iii) neither in vivo nor in vitro heat-labile kinases (tsLA32). The latter class indicates the existence of structural or functional pp60src domains that are required for transformation but do not grossly affect tyrosine kinase activity.

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Correlation between phosphorylation of a 34,000-molecular-weight protein, pp60src-associated kinase activity, and tumorigenicity in transformed and revertant vole cells

Molecular and Cellular Biology ◽

10.1128/mcb.4.1.212-215.1984 ◽

1984 ◽

Vol 4 (1) ◽

pp. 212-215

Author(s):

J F Nawrocki ◽

A F Lau ◽

A J Faras

Keyword(s):

Molecular Weight ◽

Rous Sarcoma Virus ◽

Kinase Activity ◽

Cell Types ◽

Cell Protein ◽

Protein Kinase Activity ◽

Rous Sarcoma ◽

Tumorigenic Potential ◽

Sarcoma Virus ◽

Weight Protein

The phosphorylation of a 34,000-molecular-weight (34K) cell protein, purported to be a substrate of the avian retrovirus pp60src-associated protein kinase activity, was compared in three types of Rous sarcoma virus-infected vole cells: fully transformed cells, partial revertants which are morphologically normal in appearance but retain their tumorigenic potential, and full revertants which are similar to normal vole cells in all parameters including a lack of tumorigenicity. Although similar amounts of 34K protein are present in all three cell types, phosphorylation of the 34K protein was significantly reduced in the full revertant cell type. The reduced phosphorylation occurred at the tyrosine residue.

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Role of N6-Methyladenosine in Expression of Rous Sarcoma Virus RNA: Analyses Utilizing Immunoglobulin Specific for N6-Methyladenosine

Progress in Nucleic Acid Research and Molecular Biology ◽

10.1016/s0079-6603(08)60449-3 ◽

1983 ◽

pp. 214-218 ◽

Cited By ~ 1

Author(s):

R.J. Resnick ◽

D. Noreen ◽

T.W. Munns ◽

M.L. Perdue

Keyword(s):

Rous Sarcoma Virus ◽

Rous Sarcoma ◽

Virus Rna ◽

Sarcoma Virus

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Half-life of the Rous sarcoma virus transforming protein pp60src and its associated kinase activity

Molecular and Cellular Biology ◽

10.1128/mcb.2.4.355-360.1982 ◽

1982 ◽

Vol 2 (4) ◽

pp. 355-360

Author(s):

A Ziemiecki ◽

R R Friis ◽

H Bauer

Keyword(s):

Protein Synthesis ◽

Half Life ◽

Rous Sarcoma Virus ◽

Kinase Activity ◽

Rabbit Serum ◽

Temperature Sensitive ◽

Apparent Contradiction ◽

Gag Proteins ◽

Rous Sarcoma ◽

Sarcoma Virus

The half-life of metabolically labeled pp60src of the Prague A strain of Rous sarcoma virus and of several transformation-defective, temperature-sensitive mutants was investigated by pulse-labeling infected cells with [35S]methionine, chasing for different times, and immunoprecipitating pp60src with tumor-bearing rabbit serum. These experiments showed that pp60src has a short half-life of approximately 60 min under normal physiological conditions and that the mutant pp60src proteins have similar half-lives to the wild type, irrespective of whether the cells are kept at the nonpermissive (42 degrees C) or permissive (35 degrees C) temperature. The half-life of the pp60src -associated kinase activity was determined by monitoring its decay by the immunoglobulin G heavy chain assay after the cells had been treated with several inhibitors of protein synthesis. In these experiments the kinase half-life was much longer than expected from the half-life of pp60src. The apparent contradiction between the half-lives of the kinase activity and the [35S]methionine-labeled pp60src protein could be resolved by the observation that treatment of cells with inhibitors of protein synthesis stabilized pp60src, resulting in a greatly extended half-life. Inhibitors of protein synthesis also extended the half-life of the gag precursor polypeptide, Pr76, suggesting that a host factor(s) may be required for the efficient intracellular processing of this polypeptide to the gag proteins.

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Tyrosine phosphorylation of a 50K cellular polypeptide associated with the Rous sarcoma virus transforming protein pp60src.

Molecular and Cellular Biology ◽

10.1128/mcb.2.2.199 ◽

1982 ◽

Vol 2 (2) ◽

pp. 199-206 ◽

Cited By ~ 23

Author(s):

T D Gilmore ◽

K Radke ◽

G S Martin

Keyword(s):

Protein Kinase ◽

Rous Sarcoma Virus ◽

Kinase Activity ◽

Polyacrylamide Gel Electrophoresis ◽

Fold Increase ◽

Temperature Sensitive ◽

Protein Kinase Activity ◽

Rous Sarcoma ◽

Defective Mutant ◽

Sarcoma Virus

We have examined the phosphorylation of a 50,000-dalton cellular polypeptide associated with the Rous sarcoma virus (FSV) transforming protein pp60-src. It has been shown that pp60src forms a complex with two cellular polypeptides, an 89,000-dalton heat-shock protein (89K) and a 50,000-dalton phosphoprotein (50K). The pp60src-associated protein kinase activity phosphorylates at tyrosine residues, and the 50K polypeptide present in the complex contains phosphotyrosine and phosphoserine. These observations suggest that the 50K polypeptide may be a substrate for the protein kinase activity of pp60src. To examine this possibility, we isolated the 50K polypeptide by two-dimensional polyacrylamide gel electrophoresis from lysates of uninfected or virally infected cells. Tryptic phosphopeptide analysis indicated that the 50K polypeptide isolated by this method was the same polypeptide as that complexed to pp60src. In uninfected cells or cells infected by a transformation-defective mutant, the 50K polypeptide contained phosphoserine but little or no phosphotyrosine. In cells infected by Schmidt-Ruppin or Prague RSV, there was a 40- to 50-fold increase in the quantity of phosphotyrosine in the 50K protein. Thus, the phosphorylation of the 50K polypeptide at tyrosine is dependent on the presence of pp60src. However, the 50K polypeptide isolated from cells infected by temperature-sensitive mutants of RSV was found to be phosphorylated at tyrosine at both permissive and nonpermissive temperatures; this behavior is different from that of other substrates or putative substrates of the pp60src kinase activity. It is possible that the 50K polypeptide is a high-affinity substrate of pp60src.

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Correlation between phosphorylation of a 34,000-molecular-weight protein, pp60src-associated kinase activity, and tumorigenicity in transformed and revertant vole cells.

Molecular and Cellular Biology ◽

10.1128/mcb.4.1.212 ◽

1984 ◽

Vol 4 (1) ◽

pp. 212-215 ◽

Cited By ~ 5

Author(s):

J F Nawrocki ◽

A F Lau ◽

A J Faras

Keyword(s):

Molecular Weight ◽

Rous Sarcoma Virus ◽

Kinase Activity ◽

Cell Types ◽

Cell Protein ◽

Protein Kinase Activity ◽

Rous Sarcoma ◽

Tumorigenic Potential ◽

Sarcoma Virus ◽

Weight Protein

The phosphorylation of a 34,000-molecular-weight (34K) cell protein, purported to be a substrate of the avian retrovirus pp60src-associated protein kinase activity, was compared in three types of Rous sarcoma virus-infected vole cells: fully transformed cells, partial revertants which are morphologically normal in appearance but retain their tumorigenic potential, and full revertants which are similar to normal vole cells in all parameters including a lack of tumorigenicity. Although similar amounts of 34K protein are present in all three cell types, phosphorylation of the 34K protein was significantly reduced in the full revertant cell type. The reduced phosphorylation occurred at the tyrosine residue.

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