Characterization of partially purified cytosolic protein-tyrosine kinase from porcine spleen.
Biochemical properties of a cytosolic protein-tyrosine kinase (CPTK-40) partially purified from porcine spleen were characterized and compared with p40 kinase, a cytosolic protein-tyrosine kinase from bovine thymus. When CPTK-40 was incubated with MnCl2 and (gamma-32P)ATP, only a phosphoprotein with a molecular weight of 40 kilodalton was observed. CPTK-40 efficiently phosphorylated tubulin with the rate of 0.5 nmol/min/mg. Unlike p40 kinase, casein was also a substrate for CPTK-40. Among various divalent cations tested, Co2+, Mn2+ and Mg2+ were effective metal ions for the enzyme activity. Ca2+ could also serve as a divalent cation for the activity although the rate was low. These results suggest that CPTK-40 is similar but not identical to p40 kinase.
Sakai
K
K
Department of Biochemistry, Fukui Medical School, Japan.
Nakamura
S
S
Sada
K
K
Kobayashi
T
T
Uno
H
H
Yamamura
H
H
D000818:Animals; D002413:Cations, Divalent / Q000494:pharmacology; D002417:Cattle; D003600:Cytosol / Q000201:enzymology; D008970:Molecular Weight; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000302:isolation & purification* / Q000378:metabolism; D013154:Spleen / Q000201:enzymology*; D013552:Swine; D013950:Thymus Gland / Q000201:enzymology; D014404:Tubulin / Q000378:metabolism
D002413:Cations, Divalent; D014404:Tubulin; D011505:Protein-Tyrosine Kinases