Protein tyrosine kinase–substrate interactions

2006 ◽  
Vol 16 (6) ◽  
pp. 668-675 ◽  
Author(s):  
Ron Bose ◽  
Marc A Holbert ◽  
Kerry A Pickin ◽  
Philip A Cole
Keyword(s):  
Tyrosine Kinase ◽  
Protein Tyrosine Kinase ◽  
Substrate Interactions ◽  
Protein Tyrosine ◽  
Kinase Substrate ◽  
Tyrosine Kinase Substrate

scholarly journals The protein-tyrosine kinase substrate, p81, is homologous to a chicken microvillar core protein.

1986 ◽  
Vol 102 (2) ◽  
pp. 660-669 ◽  
Author(s):  
K L Gould ◽  
J A Cooper ◽  
A Bretscher ◽  
T Hunter
Keyword(s):  
Tyrosine Kinase ◽  
Protein Tyrosine Kinase ◽  
Immunofluorescent Staining ◽  
Soluble Form ◽  
Cell Fractionation ◽  
A431 Cells ◽  
Protein Tyrosine ◽  
Kinase Substrate ◽  
Core Proteins ◽  
Tyrosine Kinase Substrate

p81, a protein-tyrosine kinase substrate previously identified in epidermal growth factor-treated A431 cells, is demonstrated to be homologous to ezrin, an 80-kD component of microvillar core proteins. p81 has been characterized using antiserum raised against purified chicken intestinal ezrin. p81, located by indirect immunofluorescent staining, is concentrated in surface projections of A431 cells such as microvilli and retraction fibers. None of the conditions of biochemical cell fractionation tested completely solubilizes p81; the insoluble p81 partitions as if associated with the cytoskeleton. The soluble form of p81 behaves as a monomer in all extraction procedures studied. EGF-stimulated phosphorylation of p81 does not appear to change its intracellular location. p81 exhibits a wide tissue distribution with highest levels of expression in small intestine, kidney, thymus, and lung. Intermediate levels are found in spleen, thymus, lymph nodes, and bone marrow, with low levels in brain, heart, and testes. p81 is undetectable in muscle and liver. In A431 cells, p81 is phosphorylated on serine and threonine residues. Upon EGF treatment, approximately 10% of p81 becomes phosphorylated on tyrosine, and the phosphorylation of threonine residues increases.

Protein-tyrosine Kinase p72 syk Is Activated by Platelet Activating Factor in Platelets

1994 ◽  
Vol 72 (06) ◽  
pp. 937-941 ◽  
Author(s):  
Karim Rezaul ◽  
Shigeru Yanagi ◽  
Kiyonao Sada ◽  
Takanobu Taniguchi ◽  
Hirohei Yamamura
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Protein Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Critical Role ◽  
Platelet Activating Factor ◽  
Kinase Assay ◽  
Potential Candidate ◽  
Protein Tyrosine ◽  
Induced Aggregation

SummaryIt has been demonstrated that activation of platelets by platelet-activating factor (PAF) results in a dramatic increase in tyrosine phosphorylation of several cellular proteins. We report here that p72 syk is a potential candidate for the protein-tyrosine phosphorylation following PAF stimulation in porcine platelets. Immunoprecipitation kinase assay revealed that PAF stimulation resulted in a rapid activation of p72 syk which peaked at 10 s. The level of activation was found to be dose dependent and could be completely inhibited by the PAF receptor antagonist, CV3988. Phosphorylation at the tyrosine residues of p72 syk coincided with activation of yllsyk. Pretreatment of platelets with aspirin and apyrase did not affect PAF induced activation of p72 syk .Furthermore, genistein, a potent protein-tyrosine-kinase inhibitor, diminished PAF-induced p72 syk activation and Ca2+ mobilization as well as platelet aggregation. These results suggest that p72 syk may play a critical role in PAF-induced aggregation, possibly through regulation of Ca2+ mobilization.

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