Role of two conserved cytoplasmic threonine residues (T410 and T412) in CD5 signaling.

CD5 is a transmembrane coreceptor that modulates activation and differentiation signals mediated by the Ag-specific receptor present on both T and B1a lymphocytes. CD5 lacks intrinsic catalytic activity, and its immunomodulatory properties result from intracellular interactions mediated by the CD5 cytoplasmic tail. The nature of these interactions is currently a ...
matter of investigation. Here, we present a selective mutagenesis analysis of two conserved threonine residues (T410 and T412) located at the membrane-proximal cytoplasmic region of CD5. These residues are contained within consensus phosphorylation motifs for protein kinase C and are shown here to be critical for in vivo protein kinase C-mediated phosphorylation of CD5. Functional studies revealed that the integrity of T410 and T412 is also critical for CD5-mediated phosphatidylcholine-specific phospholipase C (PC-PLC) activation and phorbol ester-mediated inhibition of Ab-induced internalization of CD5. These results strongly argue in favor of a role for T410 and T412 in the signaling mediated by CD5.
Mesh Terms:
Amino Acid Substitution, Animals, Antibodies, Monoclonal, Antigens, CD5, Cell Membrane, Conserved Sequence, Cytoplasm, Diglycerides, Humans, Jurkat Cells, Peptide Fragments, Phosphorylation, Protein Kinase C, Rats, Signal Transduction, Tetradecanoylphorbol Acetate, Threonine, Transfection
J. Immunol.
Date: Jan. 01, 2001
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