High tyrosine protein kinase activities in soluble and particulate fractions in bone marrow cells

High tyrosine protein kinase activities were detected in soluble and particulate forms from bone marrow cells using synthetic peptide (Glu-Asp-Ala-Glu-Tyr-Ala-Ala-Arg-Arg-Arg-Gly) as a substrate. Total activity of tyrosine protein kinase was 2.4 times higher in the soluble fraction but the specific activity was slightly higher in the particulate one. Mg2+ or Mn2+ requirements of these two enzymes for maximal activity were quite different from each other. Physiological significance of these two forms of enzymes is briefly discussed.