CPTK71, a cytosolic protein-tyrosine kinase previously purified from bovine platelets, is identical with p72syk.
In the previous study, we reported purification and characterization of cytosolic protein-tyrosine kinase, CPTK71, from bovine platelets (Nakamura, S., Yanagi, S. and Yamamura, H. (1988) Eur. J. Biochem. 174, 471-477). In the present study, we have investigated the relationship between CPTK71 and p72syk which was purified from cytosolic fraction of porcine spleen and sequenced from porcine cDNA library. The elution patterns of CPTK71 activity in each purification step closely corresponded with the pattern of immunoreactivity with p72syk. Immunoprecipitation study revealed that specific antibodies against p72syk precipitated the activity of both phosphorylating [Val5]angiotensin II and autophosphorylation of highly purified CPTK71. In addition, the same result was obtained using another anti-p72syk antibody which recognized different amino acid sequence of 72syk. From these results, we conclude that CPTK71 is identical or closely related to p72syk.
Tsubokawa
M
M
Department of Biochemistry, Fukui Medical School, Japan.
Yanagi
S
S
Sada
K
K
Nakamura
S
S
Saito
H
H
Yamamura
H
H
D000818:Animals; D001792:Blood Platelets / Q000201:enzymology*; D002417:Cattle; D003600:Cytosol / Q000201:enzymology; D004792:Enzyme Precursors / Q000378:metabolism*; D007158:Immunologic Techniques; D047908:Intracellular Signaling Peptides and Proteins; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D000072377:Syk Kinase
D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D011505:Protein-Tyrosine Kinases; D000072377:Syk Kinase