Properties of a tyrosine protein kinase from calf thymus. Response to ionic strength and divalent cations

Purification and characterization of the major tyrosine protein kinase from the human promyelocytic cell line, HL60

The major tyrosine protein kinase from HL60 (a human non-differentiated promyelocytic cell line) has been purified almost to homogeneity as judged by silver-stained SDS/PAGE. The procedure involved four chromatographic steps: DEAE-Sepharose, casein-agarose, cibacron-blue--agarose and hexyl-agarose. The purification resulted in more than 1000-fold enrichment in angiotensin II phosphorylation activity. A gel-sizing experiment, labeling with [35S]ATP[gamma s] and autophosphorylation of the enzyme in the presence of [gamma-32P]ATP, all led to the identification of a single protein species with a molecular mass of about 40 kDa. Western blot experiments showed that this protein does not belong to the src family and is not related to the abl and fes oncogene products. Phosphorylation of angiotensin II and casein by this 40-kDa human promyelocytic kinase was stimulated by high ionic strength especially from class IA metal salts. The Km for ATP was 2 microM and the Vmax 3.1 nmol.min-1.mg-1 using angiotensin II as a substrate. The kinase requires the presence of either Mn2+ or Mg2+ for full activity and utilizes ATP or dATP but not GTP as phosphate donor. Based on numerous biochemical observations, it was possible to demonstrate that kinase is different from any other tyrosine protein kinases described in the literature. This 40-kDa protein was used as a molecular tool for testing some tyrosine protein kinase inhibitors described in the literature. It is one of the rare tyrosine protein kinases purified from human cancer cells to date.

Partial purification and characterization of the lck protein-tyrosine kinase from bovine thymus

Soluble extracts prepared from bovine thymus contain an angiotensin-I-phosphorylating activity that is activated several-fold by high concentrations of NaCl. Fractionation of this protein-tyrosine kinase activity by chromatography on DEAE-cellulose yields a major diffuse peak of activity. The enzymes responsible for this activity are found at much higher levels in extracts from bovine thymus than from bovine spleen. The peak of activity from the DEAE-cellulose column can be further separated into two major peaks by chromatography on heparin-agarose. The second peak to elute from the heparin-agarose column was previously purified through several chromatographic steps to yield a 40 kDa protein-tyrosine kinase (p40). We have now partially purified the early-eluting peak of kinase activity by chromatography on columns of butyl-agarose, protamine-agarose and Sephacryl S200. The enzyme was identified following covalent modification with 5'-fluorosulphonylbenzoyladenosine (FSBA) by reactivity with anti-FSBA antibodies. This procedure labelled a series of 52-56 kDa proteins. These proteins were also recognized by polyclonal anti-peptide antibodies raised against the C-terminal 33 amino acids of p56lck, a major T lymphocyte protein-tyrosine kinase. Peptide maps of the partially purified enzyme were identical to maps generated from p56lck obtained from LSTRA cells. These data suggest that bovine thymus p56lck is responsible for the activity found in the early-eluting peak from heparin-agarose. Antibodies raised against a peptide corresponding to amino acids 39-64 of p56lck, a sequence found near the N-terminus, recognized the slower-migrating, but not the faster-migrating, form of the enzyme, indicating that a fraction of the protein had been proteolysed near the N-terminus during purification. The partially purified bovine enzyme exhibited a restricted substrate specificity in vitro and did not readily phosphorylate human erythrocyte band 3, casein or histone, but was able to phosphorylate acid-treated enolase. The dilute enzyme present in fractions eluting from chromatography columns was unable to catalyse an autophosphorylation reaction. Autophosphorylation could be detected in more concentrated enzyme samples and was readily observed in immune-complex assays. The phosphorylation of angiotensin I by bovine thymus p56lck was weakly activated by polyionic compounds such as heparin and polylysine, and was strongly activated by high concentrations of NaCl.

Stimulation by NaCl, polylysine and heparin of two forms of spleen tyrosine protein kinase immunologically related with the protein expressed by lyn oncogene

The previously isolated spleen tyrosine protein kinase, conventionally termed TPK-IIA, displaying activation by either positively or negatively charged polyelectrolytes has been further characterized. TPK-IIA is immunologically related with the tyrosine protein kinase encoded by the lyn gene, a member of src subfamily and is dramatically activated by very high NaCl concentration. The stimulatory effects of NaCl and polylysine, which are not additive, are accounted for by increased Vmax values, the Km being virtually unchanged, suggesting that both effectors probably interact with the same site(s). Stimulation of TPK-IIA by heparin appears to be partially additive to that promoted by NaCl and possibly occurring through a different mechanism. The NaCl activatory effect correlates with the electrolytic nature of synthetic peptides used as substrates, being much more consistent with neutral peptides as compared with acidic ones. Of the other three spleen tyrosine protein kinases, TPK-I shows similar biochemical and immunological features, suggestive of close relatedness with TPK-IIA, while TPK-IIB and TPK-III are neither related with the lyn protein nor with the products of three other oncogenes of the src subfamily, namely lck, hck and fyn.

Tyrosine phosphorylation in T cells is regulated by phosphatase activity: studies with phenylarsine oxide

Activation of T cells induces rapid tyrosine phosphorylation on the T-cell receptor zeta chain and other substrates. These phosphorylations can be regulated by a number of protein-tyrosine kinases (ATP: protein-tyrosine O-phosphotransferase, EC 2.7.1.112) and protein-tyrosine-phosphatases (protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48). In this study, we demonstrate that phenylarsine oxide can inhibit tyrosine phosphatases while leaving tyrosine kinase function intact. We use this reagent to investigate the effect of tyrosine phosphatase inhibition in a murine T-cell hybridoma. Increasing concentrations of phenylarsine oxide result in an increase in tyrosine phosphate on a number of intracellular substrates in unstimulated T cells, suggesting that a protein-tyrosine kinase is constitutively active in these cells. The effect of phenylarsine oxide on T cells stimulated with an anti-Thy 1 monoclonal antibody is more complex. At low concentrations of drug, there is a synergistic increase in the level of tyrosine phosphate on certain cellular substrates. At higher concentrations, anti-Thy 1-stimulated tyrosine phosphorylation is inhibited. These results indicate that tyrosine phosphorylation in T cells is tightly regulated by tyrosine phosphatases. Partial inhibition of these enzymes results in enhanced substrate phosphorylation. Inhibition of all stimulated tyrosine phosphorylation by high doses of phenylarsine oxide suggests that tyrosine kinase activity is regulated by tyrosine phosphatases.

Assay of tyrosine protein kinase activity from HL-60 by high-performance liquid chromatography for specificity studies

Using a partially purified HL-60 tyrosine protein kinase, we designed a new HPLC method for the measurement of tyrosylphosphorylation of angiotensin II. The present method uses reversed-phase chromatography and elution involving an acetonitrile gradient containing the counterion tetrabutylammonium phosphate. The peptide substrate, [gamma-32P]ATP, the cosubstrate, and 32P-labeled phosphorylated peptides were quantified online by measuring the Cerenkov effect. Injections, separation, and analysis were performed automatically. Furthermore, the method permits a direct visualization of peptide substrate phosphorylation and has a potentially universal application; i.e., it is usable with any kind of peptide in a given range of hydrophobicity. This assay was designed for specificity studies, which are of major importance at the molecular level, in order to understand active site topology and the biophysical requirements of tyrosine protein kinases. As examples, data on chromatography separations of angiotensin II analogs (five to ten amino acids in length) are presented, as well as for other peptide substrates such as RR-src, the pp60src autophosphorylation site-derived peptide, and minigastrin. We adapted our experimental conditions to accommodate crude extracts from HL-60 cells. Preliminary experiments clearly indicated that other biological sources can be used. Despite the existence of numerous methods published in the literature for the measurement of kinase activities, the method presented herein is the only one to the authors' knowledge that can be used in and has been assessed for specificity studies. Peptides do not require particular features such as charged residues (i.e., arginine) to be analyzed.

Synthetic peptides reproducing the EGF-receptor segment homologous to the pp60v-src phosphoacceptor site. Phosphorylation by tyrosine protein kinases

The octapeptide E-E-K-E-Y-H-A-E, corresponding to the amino acid sequence 841-845 of EGF receptor, whose tyrosine-845 is homologous to the main phosphorylation site of pp60v-src, has been synthesized together with seven shorter peptides encompassing variable segments around the tyrosine residue. The peptides have been employed as model substrates for inspecting the local structural determinants of three tyrosine protein kinases (TPKs), namely; TPK-IIB and TPK-III, isolated from lymphoid cells (Eur. J. Biochem. 172, 451-457 (1988] and the TPK encoded by the oncogene of Abelson murine leukemia virus. The phosphorylation order with the different peptide substrates is variable depending on the TPK used: in particular, the lysine residue at position -2 relative to tyrosine proved especially harmful with TPK-IIB, the peptides K-E-Y-H and K-E-Y-H-A-E being very poor substrates compared with their shorter derivatives devoid of the N-terminal lysine (E-Y-H and E-Y-H-A-E, respectively). Conversely, such a basic residue is well tolerated by the other two TPKs. The negative effect of the N-terminal lysine on TPK-IIB-catalyzed phosphorylation is accounted for by an increase of Km and can be overcome by the presence of additional glutamic acid(s) on that side. On the other hand, the C-terminal acidic doublet Ala-Glu specifically impairs the phosphorylation efficiency of abl-TPK, by lowering the Vmax value, the heptapeptide E-K-E-Y-H-A-E being much less readily phosphorylated than E-K-E-Y-H. Collectively, these results would indicate that the site specificity of tyrosine protein kinases results from the balance of positive and negative determinants whose influence on the catalytic activity of the individual enzymes can differ greatly.

The difference between cytosol and membrane growth-related protein kinase activities in lactating mouse mammary gland

1. A protein kinase activity which is cAMP-independent, inhibited by the bioflavonoid quercetin and probably connected to the growth of mammary gland cells was isolated and partially purified from cytosol. 2. Another protein kinase activity was demonstrated in crude membranes of lactating mouse mammary gland. 3. By the use of several different synthetic peptides as a substrate, it was demonstrated that the cytosol enzyme was a serine kinase, while the membrane protein kinase activity was mainly due to tyrosine kinase.

Purification and characterization of a tyrosine-specific protein kinase of Mr 60,000 and comparison with a kinase of Mr 56,000 from rat spleen

A tyrosine-specific protein kinase of Mr 60,000 (TK-I) was purified to near homogeneity from the particulate fraction of rat spleen. The purification procedure involved sequential chromatography of the detergent-solubilized enzyme on DEAE-Sephacel and hydroxyapatite columns. Polyacrylamide-gel electrophoresis under denaturing conditions showed one major polypeptide, of Mr 60,000. Gel filtration of the enzyme on Sephacryl S-200 column showed a single peak of kinase activity, of apparent Mr 60,000. On incubation with [gamma-32P]ATP, it showed a phosphoprotein of Mr 60,000 as a result of autophosphorylation. The autophosphorylation of the kinase occurred only at tyrosine residues. Incubation of TK-I with ATP (but not with ADP) resulted in an increase in its tyrosine-specific protein kinase activity. The time course of autophosphorylation of TK-I was very similar to the time course of activation by ATP. These and other experiments suggest that autophosphorylation might be responsible for activation of TK-I observed on incubation with ATP. A second tyrosine-specific protein kinase (TK-II) was isolated from the particulate fraction of rat spleen. A highly purified preparation of TK-II on incubation with [gamma-32P]ATP gave a major phosphoprotein, of Mr 56,000. TK-II was different from TK-I in several properties: (a) substrate specificity; (b) chromatographic behaviour; (c) phosphopeptide maps; and (d) inhibition by tosyl-lysylchloromethane. Antisera raised against TK-I did not cross-react with TK-II. These results suggest that TK-I and TK-II are distinct proteins, perhaps coded by two different genes.