Modulation of CD45 tyrosine phosphatase activity by antigen. 2001

F Lago Paz, and M Galgani, and U D'Oro, and G Matarese, and A M Masci, and S Zappacosta, and L Racioppi
Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università di Napoli Federico II, Naples, Italy.

CD45 is a widely distributed phosphatase which modulates the activity of Lck by controlling the phosphorylation status of two tyrosine residues localized in the catalytic activation loop and in the negative regulatory domain. Little is known about the regulation of CD45 activity upon T cell activation. In the present study, we found that, in resting lymphocytes, an enzymatically active fraction of CD45 molecules is associated to the CD4 coreceptor. TCR engagement by an agonist ligand markedly inhibited this pool of CD45 phosphatase without affecting the CD4 / CD45 association. These results reveal that the modulation of the CD4-associated CD45 phosphatase activity is a very early biochemical event triggered by TCR stimulation. Since the recruitment of CD4 is an initial step in the activation process, the inhibition of this pool of CD45 molecules would be crucial to prevent dephosphorylation of relevant substrates which promote the activation process.

UI MeSH Term Description Entries
D008213 Lymphocyte Activation Morphologic alteration of small B LYMPHOCYTES or T LYMPHOCYTES in culture into large blast-like cells able to synthesize DNA and RNA and to divide mitotically. It is induced by INTERLEUKINS; MITOGENS such as PHYTOHEMAGGLUTININS, and by specific ANTIGENS. It may also occur in vivo as in GRAFT REJECTION. Blast Transformation,Blastogenesis,Lymphoblast Transformation,Lymphocyte Stimulation,Lymphocyte Transformation,Transformation, Blast,Transformation, Lymphoblast,Transformation, Lymphocyte,Activation, Lymphocyte,Stimulation, Lymphocyte
D011948 Receptors, Antigen, T-Cell Molecules on the surface of T-lymphocytes that recognize and combine with antigens. The receptors are non-covalently associated with a complex of several polypeptides collectively called CD3 antigens (CD3 COMPLEX). Recognition of foreign antigen and the major histocompatibility complex is accomplished by a single heterodimeric antigen-receptor structure, composed of either alpha-beta (RECEPTORS, ANTIGEN, T-CELL, ALPHA-BETA) or gamma-delta (RECEPTORS, ANTIGEN, T-CELL, GAMMA-DELTA) chains. Antigen Receptors, T-Cell,T-Cell Receptors,Receptors, T-Cell Antigen,T-Cell Antigen Receptor,T-Cell Receptor,Antigen Receptor, T-Cell,Antigen Receptors, T Cell,Receptor, T-Cell,Receptor, T-Cell Antigen,Receptors, T Cell Antigen,Receptors, T-Cell,T Cell Antigen Receptor,T Cell Receptor,T Cell Receptors,T-Cell Antigen Receptors
D002999 Clone Cells A group of genetically identical cells all descended from a single common ancestral cell by mitosis in eukaryotes or by binary fission in prokaryotes. Clone cells also include populations of recombinant DNA molecules all carrying the same inserted sequence. (From King & Stansfield, Dictionary of Genetics, 4th ed) Clones,Cell, Clone,Cells, Clone,Clone,Clone Cell
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D000938 Antigen-Presenting Cells A heterogeneous group of immunocompetent cells that mediate the cellular immune response by processing and presenting antigens to the T-cells. Traditional antigen-presenting cells include MACROPHAGES; DENDRITIC CELLS; LANGERHANS CELLS; and B-LYMPHOCYTES. FOLLICULAR DENDRITIC CELLS are not traditional antigen-presenting cells, but because they hold antigen on their cell surface in the form of IMMUNE COMPLEXES for B-cell recognition they are considered so by some authors. Accessory Cells, Immunologic,Antigen-Presenting Cell,Immunologic Accessory Cells,Accessory Cell, Immunologic,Cell, Immunologic Accessory,Cells, Immunologic Accessory,Immunologic Accessory Cell,Antigen Presenting Cell,Antigen Presenting Cells,Cell, Antigen-Presenting,Cells, Antigen-Presenting
D000941 Antigens Substances that are recognized by the immune system and induce an immune reaction. Antigen
D015496 CD4-Positive T-Lymphocytes A critical subpopulation of T-lymphocytes involved in the induction of most immunological functions. The HIV virus has selective tropism for the T4 cell which expresses the CD4 phenotypic marker, a receptor for HIV. In fact, the key element in the profound immunosuppression seen in HIV infection is the depletion of this subset of T-lymphocytes. T4 Cells,T4 Lymphocytes,CD4-Positive Lymphocytes,CD4 Positive T Lymphocytes,CD4-Positive Lymphocyte,CD4-Positive T-Lymphocyte,Lymphocyte, CD4-Positive,Lymphocytes, CD4-Positive,T-Lymphocyte, CD4-Positive,T-Lymphocytes, CD4-Positive,T4 Cell,T4 Lymphocyte
D015704 CD4 Antigens 55-kDa antigens found on HELPER-INDUCER T-LYMPHOCYTES and on a variety of other immune cell types. They are members of the immunoglobulin supergene family and are implicated as associative recognition elements in MAJOR HISTOCOMPATIBILITY COMPLEX class II-restricted immune responses. On T-lymphocytes they define the helper/inducer subset. T4 antigens also serve as INTERLEUKIN-15 receptors and bind to the HIV receptors, binding directly to the HIV ENVELOPE PROTEIN GP120. Antigens, CD4,CD4 Molecule,CD4 Receptor,CD4 Receptors,Receptors, CD4,T4 Antigens, T-Cell,CD4 Antigen,Receptors, Surface CD4,Surface CD4 Receptor,Antigen, CD4,Antigens, T-Cell T4,CD4 Receptor, Surface,CD4 Receptors, Surface,Receptor, CD4,Surface CD4 Receptors,T-Cell T4 Antigens,T4 Antigens, T Cell
D017493 Leukocyte Common Antigens High-molecular weight glycoproteins uniquely expressed on the surface of LEUKOCYTES and their hemopoietic progenitors. They contain two FIBRONECTIN TYPE III DOMAINS and possess cytoplasmic protein tyrosine phosphatase activity, which plays a role in intracellular signaling from the CELL SURFACE RECEPTORS. Leukocyte common antigens occur as multiple isoforms that result from alternative mRNA splicing and differential usage of three exons. Antigens, CD45,CD45 Antigens,CD45R Antigens,CD45RA Antigens,CD45RO Antigens,Protein Tyrosine Phosphatase, Receptor Type, C,2H4 Antigens,B220 Antigen,B220 Antigens,CD45 Antigen,CD45R0 Antigens,CD45RB Antigens,CD45RCAntigens,L-CA Antigens,Leukocyte Common Antigen,T200 Antigens,Antigen, B220,Antigen, CD45,Antigen, Leukocyte Common,Antigens, 2H4,Antigens, B220,Antigens, CD45R,Antigens, CD45R0,Antigens, CD45RA,Antigens, CD45RB,Antigens, CD45RO,Antigens, L-CA,Antigens, Leukocyte Common,Antigens, T200,L CA Antigens
D051379 Mice The common name for the genus Mus. Mice, House,Mus,Mus musculus,Mice, Laboratory,Mouse,Mouse, House,Mouse, Laboratory,Mouse, Swiss,Mus domesticus,Mus musculus domesticus,Swiss Mice,House Mice,House Mouse,Laboratory Mice,Laboratory Mouse,Mice, Swiss,Swiss Mouse,domesticus, Mus musculus

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