scholarly journals Dephosphorylation or antibody binding to the carboxy terminus stimulates pp60c-src.

1986 ◽  
Vol 6 (12) ◽  
pp. 4467-4477 ◽  
Author(s):  
J A Cooper ◽  
C S King
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Protein Tyrosine Kinase ◽  
Kinase Activity ◽  
Antibody Binding ◽  
Carboxy Terminus ◽  
Tyrosine Kinase Activity ◽  
Protein Tyrosine ◽  
Protein Tyrosine Kinase Activity

Phosphorylation of pp60c-src at Tyr-527, six residues from the carboxy terminus, has been implicated in regulation of the protein-tyrosine kinase activity of pp60c-src. Here we show that dephosphorylation of pp60c-src by phosphatase treatment in vitro caused a 10- to 20-fold increase in pp60c-src protein-tyrosine kinase activity. Binding of specific antibody to the region of pp60c-src which contains phosphotyrosine-527 also increased kinase activity. Each treatment increased phosphorylation of added substrates and of Tyr-416 within pp60c-src by a similar mechanism that involved altered interactions with ATP and increased catalytic rate. We suggest that the phosphorylated carboxy terminus acts as an inhibitor of the protein kinase domain of pp60c-src, unless its conformation is altered by either dephosphorylation or antibody binding. The antibody additionally stimulated the phosphorylation of forms of pp60c-src that had reduced gel mobility, much like those phosphorylated in kinase reactions containing pp60c-src activated by polyomavirus medium tumor antigen. These in vitro experiments provide models for the activation of pp60c-src in cells transformed by polyomavirus. We also show that autophosphorylation of pp60c-src at Tyr-527 occurs only to a very limited extent in vitro, even when Tyr-527 is made available for phosphorylation by treatment with phosphatase. This suggests that other protein-tyrosine kinases may normally phosphorylate Tyr-527 and regulate pp60c-src in the cell.

Dephosphorylation or antibody binding to the carboxy terminus stimulates pp60c-src

1986 ◽  
Vol 6 (12) ◽  
pp. 4467-4477
Author(s):  
J A Cooper ◽  
C S King
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Protein Tyrosine Kinase ◽  
Kinase Activity ◽  
Antibody Binding ◽  
Carboxy Terminus ◽  
Tyrosine Kinase Activity ◽  
Protein Tyrosine ◽  
Protein Tyrosine Kinase Activity

Phosphorylation of pp60c-src at Tyr-527, six residues from the carboxy terminus, has been implicated in regulation of the protein-tyrosine kinase activity of pp60c-src. Here we show that dephosphorylation of pp60c-src by phosphatase treatment in vitro caused a 10- to 20-fold increase in pp60c-src protein-tyrosine kinase activity. Binding of specific antibody to the region of pp60c-src which contains phosphotyrosine-527 also increased kinase activity. Each treatment increased phosphorylation of added substrates and of Tyr-416 within pp60c-src by a similar mechanism that involved altered interactions with ATP and increased catalytic rate. We suggest that the phosphorylated carboxy terminus acts as an inhibitor of the protein kinase domain of pp60c-src, unless its conformation is altered by either dephosphorylation or antibody binding. The antibody additionally stimulated the phosphorylation of forms of pp60c-src that had reduced gel mobility, much like those phosphorylated in kinase reactions containing pp60c-src activated by polyomavirus medium tumor antigen. These in vitro experiments provide models for the activation of pp60c-src in cells transformed by polyomavirus. We also show that autophosphorylation of pp60c-src at Tyr-527 occurs only to a very limited extent in vitro, even when Tyr-527 is made available for phosphorylation by treatment with phosphatase. This suggests that other protein-tyrosine kinases may normally phosphorylate Tyr-527 and regulate pp60c-src in the cell.

scholarly journals Development of the Sensing Platform for Protein Tyrosine Kinase Activity

Biosensors ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 240
Author(s):  
Lan-Yi Wei ◽  
Wei Lin ◽  
Bey-Fen Leo ◽  
Lik-Voon Kiew ◽  
Chia-Ching Chang ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Protein Tyrosine Kinase ◽  
Kinase Activity ◽  
Significant Inhibition ◽  
Tyrosine Kinase Activity ◽  
Protein Tyrosine ◽  
Sensing Platform ◽  
Relative Standard ◽  
Protein Tyrosine Kinase Activity

A miniature tyrosinase-based electrochemical sensing platform for label-free detection of protein tyrosine kinase activity was developed in this study. The developed miniature sensing platform can detect the substrate peptides for tyrosine kinases, such as c-Src, Hck and Her2, in a low sample volume (1–2 μL). The developed sensing platform exhibited a high reproducibility for repetitive measurement with an RSD (relative standard deviation) of 6.6%. The developed sensing platform can detect the Hck and Her2 in a linear range of 1–200 U/mL with the detection limit of 1 U/mL. The sensing platform was also effective in assessing the specificity and efficacies of the inhibitors for protein tyrosine kinases. This is demonstrated by the detection of significant inhibition of Hck (~88.1%, but not Her2) by the Src inhibitor 1, an inhibitor for Src family kinases, as well as the significant inhibition of Her2 (~91%, but not Hck) by CP-724714 through the platform. These results suggest the potential of the developed miniature sensing platform as an effective tool for detecting different protein tyrosine kinase activity and for accessing the inhibitory effect of various inhibitors to these kinases.

scholarly journals Novel yeast protein kinase (YPK1 gene product) is a 40-kilodalton phosphotyrosyl protein associated with protein-tyrosine kinase activity.

1990 ◽  
Vol 10 (12) ◽  
pp. 6244-6256 ◽  
Author(s):  
D Dailey ◽  
G L Schieven ◽  
M Y Lim ◽  
H Marquardt ◽  
T Gilmore ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Protein Tyrosine Kinase ◽  
Kinase Activity ◽  
Protein Tyrosine Kinases ◽  
Tyrosine Kinase Activity ◽  
Protein Tyrosine ◽  
Protein Tyrosine Kinase Activity

Extracts of bakers' yeast (Saccharomyces cerevisiae) contain protein-tyrosine kinase activity that can be detected with a synthetic Glu-Tyr copolymer as substrate (G. Schieven, J. Thorner, and G.S. Martin, Science 231:390-393, 1986). By using this assay in conjunction with ion-exchange and affinity chromatography, a soluble tyrosine kinase activity was purified over 8,000-fold from yeast extracts. The purified activity did not utilize typical substrates for mammalian protein-tyrosine kinases (enolase, casein, and histones). The level of tyrosine kinase activity at all steps of each preparation correlated with the content of a 40-kDa protein (p40). Upon incubation of the most highly purified fractions with Mn-ATP or Mg-ATP, p40 was the only protein phosphorylated on tyrosine. Immunoblotting of purified p40 or total yeast extracts with antiphosphotyrosine antibodies and phosphoamino acid analysis of 32P-labeled yeast proteins fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the 40-kDa protein is normally phosphorylated at tyrosine in vivo. 32P-labeled p40 immunoprecipitated from extracts of metabolically labeled cells by affinity-purified anti-p40 antibodies contained both phosphoserine and phosphotyrosine. The gene encoding p40 (YPK1) was cloned from a yeast genomic library by using oligonucleotide probes designed on the basis of the sequence of purified peptides. As deduced from the nucleotide sequence of YPK1, p40 is homologous to known protein kinases, with features that resemble known protein-serine kinases more than known protein-tyrosine kinases. Thus, p40 is a protein kinase which is phosphorylated in vivo and in vitro at both tyrosine and serine residues; it may be a novel type of autophosphorylating tyrosine kinase, a bifunctional (serine/tyrosine-specific) protein kinase, or a serine kinase that is a substrate for an associated tyrosine kinase.

Novel yeast protein kinase (YPK1 gene product) is a 40-kilodalton phosphotyrosyl protein associated with protein-tyrosine kinase activity

1990 ◽  
Vol 10 (12) ◽  
pp. 6244-6256
Author(s):  
D Dailey ◽  
G L Schieven ◽  
M Y Lim ◽  
H Marquardt ◽  
T Gilmore ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Protein Tyrosine Kinase ◽  
Kinase Activity ◽  
Protein Tyrosine Kinases ◽  
Tyrosine Kinase Activity ◽  
Protein Tyrosine ◽  
Protein Tyrosine Kinase Activity

Extracts of bakers' yeast (Saccharomyces cerevisiae) contain protein-tyrosine kinase activity that can be detected with a synthetic Glu-Tyr copolymer as substrate (G. Schieven, J. Thorner, and G.S. Martin, Science 231:390-393, 1986). By using this assay in conjunction with ion-exchange and affinity chromatography, a soluble tyrosine kinase activity was purified over 8,000-fold from yeast extracts. The purified activity did not utilize typical substrates for mammalian protein-tyrosine kinases (enolase, casein, and histones). The level of tyrosine kinase activity at all steps of each preparation correlated with the content of a 40-kDa protein (p40). Upon incubation of the most highly purified fractions with Mn-ATP or Mg-ATP, p40 was the only protein phosphorylated on tyrosine. Immunoblotting of purified p40 or total yeast extracts with antiphosphotyrosine antibodies and phosphoamino acid analysis of 32P-labeled yeast proteins fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the 40-kDa protein is normally phosphorylated at tyrosine in vivo. 32P-labeled p40 immunoprecipitated from extracts of metabolically labeled cells by affinity-purified anti-p40 antibodies contained both phosphoserine and phosphotyrosine. The gene encoding p40 (YPK1) was cloned from a yeast genomic library by using oligonucleotide probes designed on the basis of the sequence of purified peptides. As deduced from the nucleotide sequence of YPK1, p40 is homologous to known protein kinases, with features that resemble known protein-serine kinases more than known protein-tyrosine kinases. Thus, p40 is a protein kinase which is phosphorylated in vivo and in vitro at both tyrosine and serine residues; it may be a novel type of autophosphorylating tyrosine kinase, a bifunctional (serine/tyrosine-specific) protein kinase, or a serine kinase that is a substrate for an associated tyrosine kinase.

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