PMID:17681949

Citation	Abudula, A, Grabbe, A, Brechmann, M, Polaschegg, C, Herrmann, N, Goldbeck, I, Dittmann, K and Wienands, J (2007) SLP-65 signal transduction requires Src homology 2 domain-mediated membrane anchoring and a kinase-independent adaptor function of Syk. J. Biol. Chem. 282:29059-66
Abstract	The family of SLPs (Src homology 2 domain-containing leukocyte adaptor proteins) are cytoplasmic signal effectors of lymphocyte antigen receptors. A main function of SLP is to orchestrate the assembly of Ca(2+)-mobilizing enzymes at the inner leaflet of the plasma membrane. For this purpose, SLP-76 in T cells utilizes the transmembrane adaptor LAT, but the mechanism of SLP-65 membrane anchoring in B cells remains an enigma. We now employed two genetic reconstitution systems to unravel structural requirements of SLP-65 for the initiation of Ca(2+) mobilization and subsequent activation of gene transcription. First, mutational analysis of SLP-65 in DT40 B cells revealed that its C-terminal Src homology 2 domain controls efficient tyrosine phosphorylation by the kinase Syk, plasma membrane recruitment, as well as downstream signaling to NFAT activation. Second, we dissected these processes by expressing SLP-65 in SLP-76-deficient T cells and found that a kinase-independent adaptor function of Syk is required to link phosphorylated SLP-65 to Ca(2+) mobilization. These approaches unmask a mechanistic complexity of SLP-65 activation and coupling to signaling cascades in that Syk is upstream as well as downstream of SLP-65. Moreover, membrane anchoring of the SLP-65-assembled Ca(2+) initiation complex, which appears to be fundamentally different from that of closely related SLP-76, does not necessarily involve a B cell-specific component.
Links	PubMed Online version:10.1074/jbc.M704043200
Keywords	Adaptor Proteins, Signal Transducing/genetics; Adaptor Proteins, Signal Transducing/metabolism; B-Lymphocytes/metabolism; Calcium/metabolism; Calcium Signaling/physiology; Cell Membrane/genetics; Cell Membrane/metabolism; Enzyme Activation/physiology; Humans; Intracellular Signaling Peptides and Proteins/genetics; Intracellular Signaling Peptides and Proteins/metabolism; Jurkat Cells; Membrane Proteins/genetics; Membrane Proteins/metabolism; Mutation; NFATC Transcription Factors/genetics; NFATC Transcription Factors/metabolism; Phosphoproteins/genetics; Phosphoproteins/metabolism; Phosphorylation; Protein-Tyrosine Kinases/genetics; Protein-Tyrosine Kinases/metabolism; T-Lymphocytes/metabolism; src Homology Domains/physiology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
HUMAN:KSYK	involved_in	GO:0006468: protein phosphorylation	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete
HUMAN:KSYK		GO:0006468: protein phosphorylation	ECO:0000314:		P		figure 5 shows SLP-65 phosphorylation by Syk	complete CACAO 6517

References

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