title: The SH2-domain of SHIP1 interacts with the SHIP1 C-terminus: impact on SHIP1/Ig-α interaction.
abstract: The SH2-containing inositol 5'-phosphatase, SHIP1, negatively regulates signal transduction from the B cell antigen receptor (BCR). The mode of coupling between SHIP1 and the BCR has not been elucidated so far. In comparison to wild-type cells, B cells expressing a mutant IgD- or IgM-BCR containing a C-terminally truncated Ig-α respond to pervanadate stimulation with markedly reduced tyrosine phosphorylation of SHIP1 and augmented activation of protein kinase B. This indicates that SHIP1 is capable of interacting with the C-terminus of Ig-α. Employing a system of fluorescence resonance energy transfer in S2 cells, we can clearly demonstrate interaction between the SH2-domain of SHIP1 and Ig-α. Furthermore, a fluorescently labeled SH2-domain of SHIP1 translocates to the plasma membrane in an Ig-α-dependent manner. Interestingly, whereas the SHIP1 SH2-domain can be pulled-down with phospho-peptides corresponding to the immunoreceptor tyrosine-based activation motif (ITAM) of Ig-α from detergent lysates, no interaction between full-length SHIP1 and the phosphorylated Ig-α ITAM can be observed. Further studies show that the SH2-domain of SHIP1 can bind to the C-terminus of the SHIP1 molecule, most probably by inter- as well as intra-molecular means, and that this interaction regulates the association between different forms of SHIP1 and Ig-α.
authors.affiliation: RWTH Aachen University, Medical Faculty, Department of Biochemistry and Molecular Immunology, Institute of Biochemistry and Molecular Biology, 52074 Aachen, Germany.
authors.forename: Oindrilla
authors.initials: O
authors.lastname: Mukherjee
authors.forename: Lars
authors.initials: L
authors.lastname: Weingarten
authors.forename: Inken
authors.initials: I
authors.lastname: Padberg
authors.forename: Catrin
authors.initials: C
authors.lastname: Pracht
authors.forename: Rileen
authors.initials: R
authors.lastname: Sinha
authors.forename: Thomas
authors.initials: T
authors.lastname: Hochdörfer
authors.forename: Stephan
authors.initials: S
authors.lastname: Kuppig
authors.forename: Rolf
authors.initials: R
authors.lastname: Backofen
authors.forename: Michael
authors.initials: M
authors.lastname: Reth
authors.forename: Michael
authors.initials: M
authors.lastname: Huber
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D019281:Dimerization; D007137:Immunoglobulin alpha-Chains / Q000378:metabolism*; D000072181:Inositol Polyphosphate 5-Phosphatases; D051379:Mice; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured; D018909:src Homology Domains
chemical_list: D007137:Immunoglobulin alpha-Chains; D011993:Recombinant Fusion Proteins; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases; C000606433:Inpp5d protein, mouse; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases