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1.
Virology ; 276(2): 339-48, 2000 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-11040125

RESUMO

The Tip protein of Herpesvirus saimiri strain 484C binds to and activates the Lck tyrosine protein kinase. Two sequences in the Tip protein were previously shown to be involved in binding to Lck. A proline-rich region, residues 132-141, binds to the SH3 domain of the Lck protein. We show here that the other Lck-binding domain, residues 104-113, binds to the carboxyl-terminal half of Lck and that this binding does not require the Lck SH3 domain. Mutated Tip containing only one functional Lck-binding domain can bind stably to Lck, although not as strongly as wild-type Tip. Interaction of Tip with Lck through either Lck-binding domain increases the activity of Lck in vivo. Simultaneous binding of both domains is required for maximal activation of Lck. The transient expression of Tip in T cells was found to stimulate both Stat3-dependent and NF-AT-dependent transcription. Mutant forms of Tip lacking one or the other of the two Lck-binding domains retained the ability to stimulate Stat3-dependent transcription. Tip lacking the proline-rich Lck-binding domain exhibited almost wild-type activity in this assay. In contrast, ablation of either Lck-binding domain abolished the ability of Tip to stimulate NF-AT-dependent transcription. Full biological activity of Tip, therefore, appears to require both Lck-binding domains.


Assuntos
Herpesvirus Saimiriíneo 2/fisiologia , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/metabolismo , Fosfoproteínas/metabolismo , Proteínas Virais/metabolismo , Sítios de Ligação , Linhagem Celular , Proteínas de Ligação a DNA/metabolismo , Ativação Enzimática , Humanos , Células Jurkat , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/química , Modelos Moleculares , Mutação , Fosfoproteínas/química , Fosfoproteínas/genética , Ligação Proteica , Estrutura Terciária de Proteína , Fator de Transcrição STAT3 , Linfócitos T/metabolismo , Linfócitos T/virologia , Transativadores/metabolismo , Proteínas Virais/química , Proteínas Virais/genética , Domínios de Homologia de src
2.
J Biol Chem ; 274(29): 20056-9, 1999 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-10400611

RESUMO

The Tip protein of herpesvirus saimiri 484 binds to the Lck tyrosine-protein kinase at two sites and activates it dramatically. Lck has been shown previously to be activated by either phosphorylation of Tyr394 or dephosphorylation of Tyr505. We examined here whether a change in the phosphorylation of either site was required for the activation of Lck by Tip. Remarkably, mutation of both regulatory sites of tyrosine phosphorylation did not prevent activation of Lck by Tip either in vivo or in a cell free in vitro system. Tip therefore appears to be able to activate Lck through an induced conformational change that does not necessarily involve altered phosphorylation of the kinase. Tip may represent the prototype of a novel type of regulator of tyrosine-protein kinases.


Assuntos
Herpesvirus Saimiriíneo 2/metabolismo , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/metabolismo , Fosfoproteínas/metabolismo , Proteínas Virais/metabolismo , Linhagem Celular , Ativação Enzimática , Humanos , Mutagênese , Fosforilação , Ligação Proteica
4.
Neurosurgery ; 35(2): 314-7; discussion 317, 1994 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-7969842

RESUMO

A case of a pituicytoma is presented that describes the clinical, pathological, and magnetic resonance imaging features of a rare tumor of the neurohypophysis. A 26-year-old woman presented with a 4-month history of dizziness and visual obscuration. A magnetic resonance image revealed a pituitary mass with suprasellar extension. The specimen obtained from a transsphenoidal decompression identified the mass as an astrocytoma of the posterior pituitary (pituicytoma). Immunohistochemical staining was positive for glial fibrillary acidic protein, S-100, and vimentin. Electron microscopy identified intermediate filaments, numerous broad cell junctions, no secretory granules, and two cellular populations with either an electron-dense or lucent cytoplasmic matrix. This case is unique in that other documented cases originating in the posterior pituitary have all been pilocytic astrocytomas, whereas this neoplasm was not a pilocytic variant. This is also the first case in the literature of a pituicytoma documented by magnetic resonance imaging. This report reviews the cytological elements of the neurohypophysis and the origin of pituicytomas and stresses the proper use of the term "pituicytoma" in relation to tumors of the posterior pituitary.


Assuntos
Astrocitoma/diagnóstico , Imageamento por Ressonância Magnética , Neoplasias Hipofisárias/diagnóstico , Adulto , Astrocitoma/patologia , Astrocitoma/radioterapia , Astrocitoma/cirurgia , Biomarcadores Tumorais/análise , Terapia Combinada , Feminino , Proteína Glial Fibrilar Ácida/análise , Humanos , Microscopia Eletrônica , Neuro-Hipófise/patologia , Neuro-Hipófise/cirurgia , Irradiação Hipofisária , Neoplasias Hipofisárias/patologia , Neoplasias Hipofisárias/radioterapia , Neoplasias Hipofisárias/cirurgia , Proteínas S100/análise , Vimentina/análise
5.
Neurosurgery ; 35(1): 148-51, 1994 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-7936138

RESUMO

Epithelioid hemangioendothelioma is an unusual vascular neoplasm with prominent cytoplasmic vacuolization representing primitive lumen formation. A case is presented of this unique vascular neoplasm in a woman with a seizure disorder who had cardiac, hepatic, and recurrent nervous system lesions. To our knowledge, this is the third known case of intracranial epithelioid hemangioendothelioma. Emphasis is placed on the indolent course of this rare neoplasm, with a recommendation for aggressive surgical treatment and diligent follow-up.


Assuntos
Neoplasias Encefálicas/patologia , Neoplasias Cardíacas/patologia , Hemangioendotelioma Epitelioide/patologia , Neoplasias Hepáticas/patologia , Neoplasias Primárias Múltiplas/patologia , Adulto , Neoplasias Encefálicas/diagnóstico por imagem , Feminino , Seguimentos , Hemangioendotelioma Epitelioide/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética , Recidiva Local de Neoplasia , Gravidez , Complicações Neoplásicas na Gravidez/patologia , Tomografia Computadorizada por Raios X
6.
J Biol Chem ; 269(18): 13529-35, 1994 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-8175787

RESUMO

In addition to membrane immunoglobulin (mIg), the B-cell antigen receptor contains Ig-alpha/Ig-beta heterodimers that link mIg to intracellular signaling molecules. To compare the ability of the cytoplasmic domains of Ig-alpha and Ig-beta to transduce signals in B- and T-cells, we constructed chimeric genes encoding the extracellular and transmembrane domains of human CD8 alpha and the cytoplasmic domain of murine Ig-alpha (CD8/Ig-alpha) or Ig-beta (CD8/Ig-beta). In murine B-cell hybridoma LK 35.2 cells, antibody-mediated cross-linking of mIg, CD8/Ig-alpha, or CD8/Ig-beta induced similar increases in intracellular calcium levels and protein tyrosine phosphorylation. Substitution of alanine for the conserved leucine, but not the conserved isoleucine, residue within the putative activation motif of CD8/Ig-beta destroyed signaling ability. In murine T-cell hybridoma DO-11.10 cells, cross-linking of the T-cell antigen receptor, CD8/Ig-alpha, or CD8/Ig-beta stimulated equivalent protein tyrosine phosphorylation and interleukin-2 production. Thus, the cytoplasmic domains of Ig-alpha and Ig-beta are equally capable of initiating early signaling events downstream of B- and T-cell antigen receptors as well as evoking a complete biological effector response in lymphocytes.


Assuntos
Antígenos CD , Linfócitos B/imunologia , Ativação Linfocitária , Receptores de Antígenos de Linfócitos B/imunologia , Linfócitos T/imunologia , Animais , Sequência de Bases , Antígenos CD79 , Antígenos CD8/imunologia , Reagentes de Ligações Cruzadas , Primers do DNA , Humanos , Imunoglobulinas/genética , Imunoglobulinas/imunologia , Leucina/genética , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/imunologia , Camundongos , Dados de Sequência Molecular , Mutação , Fosforilação , Receptores de Antígenos de Linfócitos B/genética , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/imunologia , Transdução de Sinais , Tirosina/metabolismo
7.
Adv Exp Med Biol ; 365: 23-34, 1994.
Artigo em Inglês | MEDLINE | ID: mdl-7887308

RESUMO

In B lymphocytes, the cytoplasmic domains of the membrane immunoglobulin-associated heterodimeric Ig-alpha and Ig-beta proteins link membrane immunoglobulin to intracellular signalling molecules. We constructed chimeric genes encoding the extracellular and transmembrane domain of human CD8 alpha and the cytoplasmic domain of Ig-alpha or Ig-beta and examined the ability of the chimeric proteins to induce signalling in the murine B-cell lymphoma A20. Crosslinking of CD8/Ig-alpha or CD8/Ig-beta induced both calcium mobilization and protein tyrosine phosphorylation, although induction by CD8/Ig-alpha was somewhat stronger. We also carried out mutagenesis of residues within the "Reth" motif of the CD8/Ig-beta cytoplasmic domain and determined the effects of these mutations on signalling in the murine B-cell hybridoma LK 35.2. Mutants in which alanine was substituted for glutamine 202, threonine 205, and isoleucine 209 retained the ability to induce protein tyrosine phosphorylation and calcium mobilization. In contrast, substitution of alanine for leucine 198 abrogated these responses, suggesting a critical role for this residue in interaction with cytoplasmic signalling proteins.


Assuntos
Linfócitos B/imunologia , Receptores de Antígenos de Linfócitos B/metabolismo , Transdução de Sinais , Sequência de Aminoácidos , Animais , Sequência de Bases , Antígenos CD8/genética , Cálcio/metabolismo , Primers do DNA , Citometria de Fluxo , Humanos , Hibridomas/imunologia , Linfoma de Células B/imunologia , Camundongos , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Receptores de Antígenos de Linfócitos B/genética , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Células Tumorais Cultivadas
9.
Mol Cell Biol ; 13(3): 1651-6, 1993 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8441403

RESUMO

Expression of the CD45 tyrosine protein phosphatase is required for the response of functional lymphocytes to stimulation through the antigen receptor. One or more of its substrates may therefore be essential for signal transduction during lymphocyte activation. We have studied the phosphorylation of the closely related lck, fyn, and c-src tyrosine protein kinases in leukemic murine T-cell lines that have lost the expression of CD45. The phosphorylation of the lck kinase at an inhibitory site of tyrosine phosphorylation, Tyr-505, was increased by two-, six-, and eightfold in three different cell lines. Phosphorylation of the fyn kinase at the homologous site, Tyr-531, was unaltered in one of these cell lines, but increased by 2.5-fold in the two others. The phosphorylation of p60c-src at the homologous tyrosine was essentially unchanged in the one CD45-negative cell line in which it was examined. The expression of CD45 therefore regulates the phosphorylation and potentially the activity of the lck and fyn tyrosine protein kinases, but the effect on the lck kinase is much greater than on the fyn kinase. This finding and the observation that CD45 had no effect on the phosphorylation of p60c-src suggest that CD45 exhibits polypeptide substrate specificity in vivo. Additionally, these findings are consistent with the hypothesis that the unresponsiveness of CD45-negative lymphoid cells to antigenic stimulation is due largely to hyperphosphorylation of the lck kinase.


Assuntos
Regulação Enzimológica da Expressão Gênica , Antígenos Comuns de Leucócito/metabolismo , Proteínas Tirosina Fosfatases/metabolismo , Proteínas Tirosina Quinases/metabolismo , Linfócitos T/metabolismo , Animais , Proteína Tirosina Quinase CSK , Linhagem Celular , Leucemia Experimental/metabolismo , Antígenos Comuns de Leucócito/genética , Proteína Tirosina Quinase p56(lck) Linfócito-Específica , Camundongos , Mapeamento de Peptídeos , Fosforilação , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-fyn , Especificidade por Substrato , Linfócitos T/citologia , Linfócitos T/imunologia , Tirosina/metabolismo , Quinases da Família src
10.
Proc Natl Acad Sci U S A ; 90(4): 1402-6, 1993 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-8433999

RESUMO

Stimulation of tyrosine phosphorylation is an early and important event in antigen-induced T-cell activation. T-cell clones deficient in expression of CD45, a transmembrane protein-tyrosine-phosphatase (protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48), are impaired in their ability to respond to either antigen or T-cell receptor cross-linking. Analysis of the CD45-deficient CD8+ T-cell clone L3M-93 demonstrates that the Src family members p56lck and p59fyn show increased immunoreactivity with anti-phosphotyrosine antibody and exhibit decreased kinase activity. The site of increased tyrosine phosphorylation in Src family members was identified by comparison of cyanogen bromide peptide maps. Phosphorylation of the C-terminal phosphopeptide, containing the negative regulatory site of tyrosine phosphorylation, from the CD45-deficient cells was increased 8-fold for p56lck and 2-fold for p59fyn. These data suggest that CD45 dephosphorylates the negative regulatory site of multiple Src family members in the cytotoxic T-lymphocyte clone L3 and show a correlation between the ability to respond efficiently to antigen and the dephosphorylation of Src family members by CD45.


Assuntos
Genes src , Antígenos Comuns de Leucócito/metabolismo , Proteínas Tirosina Fosfatases/metabolismo , Proteínas Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Receptores de Antígenos de Linfócitos T/fisiologia , Transdução de Sinais , Linfócitos T/imunologia , Animais , Membrana Celular/fisiologia , Células Clonais , Brometo de Cianogênio , Immunoblotting , Ativação Linfocitária , Proteína Tirosina Quinase p56(lck) Linfócito-Específica , Fragmentos de Peptídeos/isolamento & purificação , Mapeamento de Peptídeos , Fosforilação , Proteínas Proto-Oncogênicas c-fyn
11.
J Virol ; 66(12): 7406-13, 1992 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-1279202

RESUMO

Temperature-sensitive mutants of the lck tyrosine protein kinase were created by the introduction of mutations known to cause temperature sensitivity of the v-src tyrosine protein kinase of Rous sarcoma virus. p56lck activated by mutation of the regulatory site of tyrosine phosphorylation, Tyr-505, to Phe transforms fibroblasts in culture. Mutations identical to those responsible for the temperature-sensitive phenotypes of the tsNY68 and tsNY72-4 v-src mutants rendered this activated lck gene temperature sensitive for both morphological transformation and induction of growth in soft agar. The mutant proteins were incapable of cellular transformation at the nonpermissive temperature in part because of failure of the lck protein to accumulate to normal levels. Morphological transformation of fibroblasts was detectable within 24 h of a shift of cells to the permissive temperature and was essentially complete in 48 to 72 h. These mutants should prove useful for the study of the function of the lck kinase in hematopoietic cells.


Assuntos
Vírus do Sarcoma Aviário/genética , Proteínas Oncogênicas Virais/genética , Proteínas Oncogênicas Virais/metabolismo , Proteínas Tirosina Quinases/genética , Proteínas Tirosina Quinases/metabolismo , Sequência de Aminoácidos , Animais , Vírus do Sarcoma Aviário/enzimologia , Sequência de Bases , Transformação Celular Viral , Células Cultivadas , Estabilidade Enzimática , Escherichia coli/genética , Cinética , Proteína Tirosina Quinase p56(lck) Linfócito-Específica , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Oligodesoxirribonucleotídeos , Oncogenes , Fosfotirosina , Ratos , Homologia de Sequência de Aminoácidos , Temperatura , Termodinâmica , Tirosina/análogos & derivados , Tirosina/análise
12.
J Antibiot (Tokyo) ; 45(12): 1914-8, 1992 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-1490883

RESUMO

A practical process is described for the large-scale isolation of pentostatin, an adenosine deaminase inhibitor used clinically for the treatment of interferon-refractory hairy cell leukemia. The identities of minor components in the fermentation beer, including 2'-deoxyguanosine, are also reported.


Assuntos
Pentostatina/química , Pentostatina/isolamento & purificação , Streptomyces antibioticus/química , Cromatografia Líquida de Alta Pressão , Cromatografia por Troca Iônica , Desoxiguanosina/química , Fermentação , Espectroscopia de Ressonância Magnética
13.
Oncogene ; 7(10): 1949-55, 1992 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-1408136

RESUMO

p56lck is a lymphoid cell-specific member of the src family of cytoplasmic tyrosine kinases. In helper and cytotoxic T cells it is physically associated with the CD4 and CD8 surface antigens and appears to play a role in signal transduction during T-cell activation. p56lck contains both an SH3 and an SH2 Src homology domain. Such domains have been suggested to play a role in the regulation of the activity or function of both receptor and non-receptor tyrosine protein kinases. Deletion of either or both domains in p56lck was found here to activate the protein and to lead to increased phosphorylation of the autophosphorylation site, Tyr-394, in vivo. These findings are consistent with the hypothesis that these domains participate in repression of the kinase activity of p56lck. None of the deleted forms was capable of transformation of fibroblasts. Deletion of the SH3 domain of a constitutively activated form of p56lck, p56lckF505, did not diminish the transforming activity of this protein. This suggests that this domain is dispensable for the transformation of fibroblasts by p56lck. In contrast, deletion of the SH2 domain abolished the transforming potential of activated p56lckF505. However, interpretation of this effect is made somewhat difficult because the mutation also lowered the steady-state abundance of the protein.


Assuntos
Proteínas Tirosina Quinases/fisiologia , Proteínas Proto-Oncogênicas/fisiologia , Animais , Sequência de Bases , Transformação Celular Neoplásica , Proteína Tirosina Quinase p56(lck) Linfócito-Específica , Dados de Sequência Molecular , Mutação , Fosforilação , Ratos , Relação Estrutura-Atividade
14.
Surg Neurol ; 37(5): 361-5, 1992 May.
Artigo em Inglês | MEDLINE | ID: mdl-1631761

RESUMO

Although the pituitary gland is known to harbor metastatic deposits, it is a rare occurrence for a metastatic deposit to appear in a pituitary adenoma. A case is presented of an adenocarcinoma metastatic in an acromegalic patient with a pituitary adenoma. This report adds to the literature of the unusual phenomenon of neoplasm-to-neoplasm metastasis.


Assuntos
Adenocarcinoma/secundário , Adenoma/metabolismo , Hormônio do Crescimento/metabolismo , Neoplasias Hipofisárias/secundário , Adenoma/diagnóstico , Adenoma/cirurgia , Idoso , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Seguimentos , Humanos , Imageamento por Ressonância Magnética , Masculino , Neoplasias Hipofisárias/diagnóstico , Neoplasias Hipofisárias/metabolismo , Tomografia Computadorizada por Raios X
15.
J Med Chem ; 34(7): 1935-43, 1991 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-2066966

RESUMO

A series of renin inhibitors containing ester side chains at the P2 subsite are potent inhibitors of primate renin. Derivatives containing the diol isostere (ACDMH) at P1-P1' were the most potent inhibitors. Moderate selectivity for renin was observed relative to the closely related aspartic proteinase cathepsin D. The prototype compound, 4 (PD 132002), inhibited pepsin only weakly. In both high-renin normotensive and high-renin renal hypertensive monkeys, 4 produced substantial reductions in blood pressure after oral administration of 30 mg/kg. The maximum drop in blood pressure observed (24 +/- 4 mmHg) in the renal hypertensive monkey model was comparable to the drop produced by an intravenous infusion of saralasin at a maximally effective dose. Both the magnitude and duration of the oral antihypertensive effect of 4 is greater than that produced by enalkiren, CGP-38560, or CP-80794 by direct comparison in the same hypertensive monkey model. The malonate ester derivatives were prepared as ca. 65:35 mixtures of epimers. The kinetics of epimerization of 4 were investigated in detail, and it was shown to equilibrate rapidly at physiological pH (t1/2 less than 2 min). Fractional crystallization was employed to obtain the individual diastereomers in greater than 98% purity, which were indistinguishable in terms of their activity in vitro or in vivo, presumably due to rapid epimerization under the testing conditions.


Assuntos
Dipeptídeos/síntese química , Morfolinas/síntese química , Renina/antagonistas & inibidores , Administração Oral , Animais , Pressão Sanguínea/efeitos dos fármacos , Catepsina D/antagonistas & inibidores , Dipeptídeos/uso terapêutico , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/uso terapêutico , Ésteres , Humanos , Hipertensão Renal/tratamento farmacológico , Imidazóis/síntese química , Imidazóis/farmacologia , Macaca fascicularis , Modelos Moleculares , Morfolinas/uso terapêutico , Oligopeptídeos/uso terapêutico , Renina/sangue , Estereoisomerismo , Relação Estrutura-Atividade
17.
Oncogene ; 5(6): 921-3, 1990 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-1688326

RESUMO

We have found that the transfer of gel-fractionated proteins to membranes facilitates phosphopeptide mapping. Nitrocellulose proves to be an excellent matrix for both cyanogen bromide cleavage and proteolytic digestion. Digestion of p56lck bound to a nitrocellulose membrane with cyanogen bromide or trypsin generated patterns of phosphopeptides indistinguishable from those produced by digestion of p56lck eluted from a gel. Immobilon-P and nylon membranes can also be used for proteolytic mapping, but not for cyanogen bromide cleavage. Since the use of membrane-bound protein eliminates the need for elution and precipitation of the protein, analysis is rapid. In addition, the recovery of the peptides from proteins digested on membranes is better and more consistent than it is from eluted and precipitated proteins.


Assuntos
Brometo de Cianogênio , Etorfina , Membranas Artificiais , Metotrimeprazina , Mapeamento de Peptídeos/métodos , Proteínas/metabolismo , Animais , Colódio/metabolismo , Combinação de Medicamentos , Proteína Tirosina Quinase p56(lck) Linfócito-Específica , Camundongos , Nylons , Polivinil , Proteínas Tirosina Quinases/metabolismo , Timoma/metabolismo , Timoma/patologia , Neoplasias do Timo/metabolismo , Neoplasias do Timo/patologia , Neoplasias do Timo/ultraestrutura , Tripsina/farmacologia , Células Tumorais Cultivadas/efeitos dos fármacos , Células Tumorais Cultivadas/patologia , Células Tumorais Cultivadas/ultraestrutura
18.
Proc Natl Acad Sci U S A ; 86(22): 8959-63, 1989 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-2530588

RESUMO

CD45 is a family of high molecular weight leukocyte cell surface glycoproteins. Recently, two related subregions of the cytoplasmic domain of CD45 have been shown to have 30-40% amino acid identity with a human placental protein phosphotyrosine phosphatase, and CD45 isolated from human spleen was found to exhibit intrinsic protein phosphotyrosine phosphatase (EC 3.1.3.48) activity. In the present studies, we demonstrate that each of the known isoforms of murine CD45 has an equivalent basal level of protein phosphotyrosine phosphatase activity and establish that this enzymatic activity is associated with the cytoplasmic domain of the glycoprotein. Studies with three independent sets of well-characterized parental CD45+, mutant CD45-, and revertant CD45+ lymphoma cell lines indicate that loss of CD45 increases the phosphorylation of the src-related leukocyte-specific tyrosine protein kinase p56lck on tyrosine-505, a putative negative regulatory site. This suggests that CD45 may play a role in leukocyte growth regulation by altering the kinase activity of p56lck.


Assuntos
Antígenos de Diferenciação/genética , Expressão Gênica , Antígenos de Histocompatibilidade/genética , Glicoproteínas de Membrana/genética , Proteínas Tirosina Quinases/genética , Animais , Antígenos de Diferenciação/imunologia , Linhagem Celular , Antígenos de Histocompatibilidade/imunologia , Immunoblotting , Cinética , Antígenos Comuns de Leucócito , Ativação Linfocitária , Linfoma/enzimologia , Linfoma/imunologia , Camundongos , Mutação , Fragmentos de Peptídeos/isolamento & purificação , Fosforilação , Proteínas Tirosina Quinases/metabolismo , Linfócitos T/enzimologia , Linfócitos T/imunologia , Tripsina
19.
Science ; 245(4916): 407-9, 1989 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-2787934

RESUMO

The CD4 and CD8 T cell receptor accessory molecules can both be isolated from T lymphocytes in association with p56lck, a membrane-associated, cytoplasmic tyrosine protein kinase that is expressed exclusively in lymphoid cells. The enzymatic activity of p56lck may therefore be regulated by CD4 and CD8 and be important in antigen-induced T cell activation. Exposure of human T cells and some mouse T cells to the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA), an activator of protein kinase C, caused the dissociation of p56lck and CD4. Activation of protein kinase C may therefore interrupt regulation of p56lck by CD4 and alter the ability of p56lck to interact with polypeptide substrates. In contrast, exposure of cells to TPA did not cause dissociation of p56lck and CD8. Regulation of p56lck by CD4 may therefore differ from regulation by CD8.


Assuntos
Antígenos de Diferenciação de Linfócitos T/imunologia , Proteína Quinase C/metabolismo , Proteínas Tirosina Quinases/metabolismo , Linfócitos T/imunologia , Animais , Linhagem Celular , Ativação Enzimática , Humanos , Leucemia de Células T , Proteína Tirosina Quinase p56(lck) Linfócito-Específica , Fosforilação , Testes de Precipitina , Acetato de Tetradecanoilforbol/farmacologia , Células Tumorais Cultivadas
20.
Oncogene ; 4(3): 265-72, 1989 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-2468122

RESUMO

p56lck, the tyrosine protein kinase encoded by the lck gene, is expressed at a 40-fold elevated level in the LSTRA cell line. This is associated with increased tyrosine phosphorylation of cellular proteins. We have asked here whether the increased tyrosine protein phosphorylation is due to an altered activity of the protein or to the unusually high level of p56lck. In vitro protein kinase assays showed that neither the specific activity nor the affinity of p56lck for two different substrates was abnormal in LSTRA cells. Additionally, analysis of the phosphorylation of p56lck in LSTRA and other cell lines showed that the protein was phosphorylated extensively at a negative-regulatory site, Tyr 505, in all of the cells examined. Since the primary structure of the p56lck expressed at a high level in LSTRA cells is the same as that found in normal thymus and we found no evidence of activation of the protein by dephosphorylation, it appears that high levels of p56lck can induce increased tyrosine protein phosphorylation in lymphoid cells. In contrast, high levels of the closely related protein, p60c-src have no significant effect on tyrosine protein phosphorylation in fibroblasts. The regulation of the protein kinase activity of p56lck in lymphoid cells may therefore differ from the regulation of p60c-src in fibroblasts.


Assuntos
Linfócitos/enzimologia , Fosfoproteínas/metabolismo , Proteínas Tirosina Quinases/metabolismo , Animais , Western Blotting , Linhagem Celular , Eletroforese em Gel Bidimensional , Ponto Isoelétrico , Camundongos , Peso Molecular , Fosforilação , Fosfotirosina , Tirosina/análogos & derivados , Tirosina/imunologia
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