Berkow RL, Dodson RW, Kraft AS. Human neutrophils contain distinct cytosolic and particulate tyrosine kinase activities: possible role in neutrophil activation.
BIOCHIMICA ET BIOPHYSICA ACTA 1989;
997:292-301. [PMID:
2765566 DOI:
10.1016/0167-4838(89)90200-8]
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Abstract
Tyrosine protein kinase activities were partially purified from circulating human neutrophils. Purification steps involved sequential chromatography on DEAE-Sephacel, gel filtration and affinity chromatography on a column composed of a glutamine:tyrosine copolymer linked to AH-Sepharose. The results indicate that human neutrophils contain a tyrosine kinase activity in the 150,000 x g cytosolic fraction which is distinct from the activity in a detergent extractable 150,000 x g particulate fraction. These enzyme activities are dependent on the divalent cations Mn2+ and Mg2+. Kinetics for the phosphorylation of a glutamine:tyrosine copolymer substrate demonstrated an apparent Km for the cytosolic tyrosine kinase activity of 22.3 +/- 0.3 microM, and an apparent Km for the particulate extract activity of 42.7 +/- 6.0 microM. By gel filtration chromatography, the cytosolic and particulate tyrosine kinase activities have approximate molecular masses of 80-90 and 50-60 kDa, respectively. The particulate but not the cytosolic neutrophil tyrosine kinase activity was inhibited by a novel tyrosine kinase inhibitor ST638. ST638 inhibited superoxide production in intact neutrophils stimulated with the chemotactic peptide F-Met-Leu-Phe, opsonized zymosan particles, and sodium fluoride. ST638 did not, however, inhibit superoxide production in neutrophils stimulated with phorbol myristate acetate or the calcium ionophore, A23187.
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