A new tyrosine phosphorylation site in PLC gamma 1: the role of tyrosine 775 in immune receptor signaling
| Autor: | Laurie Graham, Ezio Bonvini, Karen Debell, Carmen J. Serrano, Barbara L. Rellahan, Maria Concetta Veri, Ilona G. Reischl, Rashmi Rawat |
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| Rok vydání: | 2005 |
| Předmět: |
Immunology
Molecular Sequence Data Receptors Antigen T-Cell Receptors Antigen B-Cell Protein tyrosine phosphatase Biology Transfection Receptor tyrosine kinase Phosphorylation cascade Cell Line Tyrosine Phosphorylation Site Diglycerides chemistry.chemical_compound Jurkat Cells Immunology and Allergy Animals Humans Protein phosphorylation Amino Acid Sequence Tyrosine Phosphorylation NFATC Transcription Factors Phospholipase C gamma Nuclear Proteins Tyrosine phosphorylation Molecular biology DNA-Binding Proteins Isoenzymes Transcription Factor AP-1 chemistry Type C Phospholipases biology.protein Mutagenesis Site-Directed Calcium Cattle Signal Transduction Transcription Factors |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 0022-1767 |
| Popis: | Phospholipase Cγ (PLCγ) is a ubiquitous gatekeeper of calcium mobilization and diacylglycerol-mediated events induced by the activation of Ag and growth factor receptors. The activity of PLCγ is regulated through its controlled membrane translocation and tyrosine (Y) phosphorylation. Four activation-induced tyrosine phosphorylation sites have been previously described (Y472, Y771, Y783, and Y1254), but their specific roles in Ag receptor-induced PLCγ1 activation are not fully elucidated. Unexpectedly, we found that the phosphorylation of a PLCγ1 construct with all four sites mutated to phenylalanine was comparable with that observed with wild-type PLCγ1, suggesting the existence of an unidentified site(s). Sequence alignment with known phosphorylation sites in PLCγ2 indicated homology of PLCγ1 tyrosine residue 775 (Y775) with PLCγ2 Y753, a characterized phosphorylation site. Tyrosine 775 was characterized as a phosphorylation site using phospho-specific anti-Y775 antiserum, and by mutational analysis. Phosphorylation of Y775 did not depend on the other tyrosines, and point mutation of PLCγ1 Y775, or the previously described Y783, substantially reduced AgR-induced calcium, NF-AT, and AP-1 activation. Mutation of Y472, Y771, and Y1254 had no effect on overall PLCγ1 phosphorylation or activation. Although the concomitant mutation of Y775 and Y783 abolished downstream PLCγ1 signaling, these two tyrosines were sufficient to reconstitute the wild-type response in the absence of functional Y472, Y771, and Y1254. These data establish Y775 as a critical phosphorylation site for PLCγ1 activation and confirm the functional importance of Y783. |
| Databáze: | OpenAIRE |
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