scholarly journals Molecular events in cells transformed by Rous Sarcoma virus.

1980 ◽  
Vol 87 (2) ◽  
pp. 319-325 ◽  
Author(s):  
R L Erikson ◽  
A F Purchio ◽  
E Erikson ◽  
M S Collett ◽  
J S Brugge
Keyword(s):  
Protein Kinase ◽  
Rous Sarcoma Virus ◽  
Kinase Activity ◽  
Protein Kinase Activity ◽  
Wild Type ◽  
Dependent Protein Kinase ◽  
Rous Sarcoma ◽  
Sarcoma Virus ◽  
Dependent Protein ◽  
Transforming Gene

The Rous sarcoma virus (RSV) transforming gene product has been identified and characterized as a phosphoprotein with a molecular weight of 60,000, denoted pp60src. Partially purified pp60src displays a closely associated phosphotransferase activity with the unusual specificity of phosphorylating tyrosine residues in a variety of proteins. That the enzymatic activity observed is actually encoded by the RSV-transforming gene is indicated by the comparison of the pp60src-protein kinase isolated from cells tranformed by a wild-type RSV or by a RSV temperature-sensitive transformation mutant; these experiments revealed that the latter enzyme had a half-life of 3 min at 41 degrees C, whereas that of the wild-type enzyme was 20 min. Evidence is now beginning to accumulate showing that viral pp60src expresses its protein kinase activity in transformed cells as well as in vitro because at least one cellular protein has been identified as a substrate for this activity of pp60src. Although the protein kinase activity associated with pp60src is itself cyclic AMP (cAMP) independent, the molecule contains at least one serine residue that is directly phosphorylated by the cellular cAMP-dependent protein kinase, thus suggesting that the viral transforming gene product may be regulated indirectly by the level of cAMP. The significance of this latter observation must be regarded from the point of view that the RSV src gene is apparently derived from a normal cellular gene that seemingly expresses in normal uninfected cells a phosphoprotein structurally and functionally closely related to pp60src. This celluar protein, found in all vertebrate species tested, also is a substrate for a cAMP-dependent protein kinase of normal cells, and, therefore, may be evolved to function in a regulatory circuit involving cAMP.

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

1982 ◽  
Vol 2 (2) ◽  
pp. 199-206 ◽  
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.

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

1982 ◽  
Vol 2 (2) ◽  
pp. 199-206
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.

scholarly journals Staurosporine inhibits tyrosine-specific protein kinase activity of Rous sarcoma virus transforming protein p60.

1987 ◽  
Vol 40 (5) ◽  
pp. 706-708 ◽  
Author(s):  
HIROFUMI NAKANO ◽  
EIJI KOBAYASHI ◽  
ISAMI TAKAHASHI ◽  
TATSUYA TAMAOKI ◽  
YASUKO KUZUU ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Rous Sarcoma Virus ◽  
Kinase Activity ◽  
Specific Protein ◽  
Protein Kinase Activity ◽  
Rous Sarcoma ◽  
Sarcoma Virus ◽  
Specific Protein Kinase

Amino acid alterations within a highly conserved region of the Rous sarcoma virus src gene product pp60src inactivate tyrosine protein kinase activity

1984 ◽  
Vol 4 (5) ◽  
pp. 862-866
Author(s):  
D L Bryant ◽  
J T Parsons
Keyword(s):  
Amino Acid ◽  
Protein Kinase ◽  
Rous Sarcoma Virus ◽  
Kinase Activity ◽  
Mutant Virus ◽  
Protein Kinase Activity ◽  
Rous Sarcoma ◽  
Src Gene ◽  
Tyrosine Protein Kinase ◽  
Sarcoma Virus

Bisulfite mutagenesis techniques have been used to introduce single-point mutations within a region of the Rous sarcoma virus src gene defined by a BglI restriction endonuclease cleavage site. The mutants of Rous sarcoma virus that are produced by these techniques encode src proteins which contain single amino acid changes within a highly conserved amino acid sequence encompassing residues 430 to 433. DNA from the mutants CHpm26 ( Ala430 to Val), CHpm9 ( Pro431 to Ser), CHpm6 ( Glu432 to Lys), and CHpm65 ( Ala433 to Thr) each failed to transform chicken cells upon transfection, whereas DNA from CHpm59 (a third base alteration in the codon for Glu432 ) readily transformed chicken cells. Analysis of immune complexes containing the altered src proteins indicates that these proteins have decreased tyrosine protein kinase activity in vitro. In vivo labeling of cells infected with the mutant virus revealed diminished levels of the tyrosine-phosphorylated 34,000-molecular-weight protein. These data indicate that mutations within the sequence Ala430 - Pro431 - Glu432 - Ala433 lead to alterations in pp60src-specific tyrosine protein kinase activity and a concomitant loss of transforming potential of the mutant virus.

scholarly journals Amino acid alterations within a highly conserved region of the Rous sarcoma virus src gene product pp60src inactivate tyrosine protein kinase activity.

1984 ◽  
Vol 4 (5) ◽  
pp. 862-866 ◽  
Author(s):  
D L Bryant ◽  
J T Parsons
Keyword(s):  
Amino Acid ◽  
Protein Kinase ◽  
Rous Sarcoma Virus ◽  
Kinase Activity ◽  
Mutant Virus ◽  
Protein Kinase Activity ◽  
Rous Sarcoma ◽  
Src Gene ◽  
Tyrosine Protein Kinase ◽  
Sarcoma Virus

Bisulfite mutagenesis techniques have been used to introduce single-point mutations within a region of the Rous sarcoma virus src gene defined by a BglI restriction endonuclease cleavage site. The mutants of Rous sarcoma virus that are produced by these techniques encode src proteins which contain single amino acid changes within a highly conserved amino acid sequence encompassing residues 430 to 433. DNA from the mutants CHpm26 ( Ala430 to Val), CHpm9 ( Pro431 to Ser), CHpm6 ( Glu432 to Lys), and CHpm65 ( Ala433 to Thr) each failed to transform chicken cells upon transfection, whereas DNA from CHpm59 (a third base alteration in the codon for Glu432 ) readily transformed chicken cells. Analysis of immune complexes containing the altered src proteins indicates that these proteins have decreased tyrosine protein kinase activity in vitro. In vivo labeling of cells infected with the mutant virus revealed diminished levels of the tyrosine-phosphorylated 34,000-molecular-weight protein. These data indicate that mutations within the sequence Ala430 - Pro431 - Glu432 - Ala433 lead to alterations in pp60src-specific tyrosine protein kinase activity and a concomitant loss of transforming potential of the mutant virus.

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