Identification of a novel immunoreceptor tyrosine-based activation motif-containing molecule, STAM2, by mass spectrometry and its involvement in growth factor and cytokine receptor signaling pathways.
In an effort to clone novel tyrosine-phosphorylated substrates of the epidermal growth factor receptor, we have initiated an approach coupling affinity purification using anti-phosphotyrosine antibodies to mass spectrometry-based identification. Here, we report the identification of a signaling molecule containing a Src homology 3 domain as well as an immunoreceptor tyrosine-based activation motif (ITAM). This molecule is 55% identical to a previously isolated molecule designated signal transducing adaptor molecule (STAM) that was identified as an interleukin (IL)-2-induced phosphoprotein and is therefore designated STAM2. Tyrosine phosphorylation of STAM2 is induced by growth factors such as epidermal growth factor and platelet-derived growth factor as well as by cytokines like IL-3. Several of the deletion mutants tested except the one containing only the amino-terminal region underwent tyrosine phosphorylation upon growth factor stimulation, implying that STAM2 is phosphorylated on several tyrosine residues. STAM2 is downstream of the Jak family of kinases since coexpression of STAM2 with Jak1 or Jak2 but not an unrelated Tec family kinase, Etk, resulted in its tyrosine phosphorylation. In contrast to epidermal growth factor receptor-induced phosphorylation, this required the ITAM domain since mutants lacking this region did not undergo tyrosine phosphorylation. Finally, overexpression of wild type STAM2 led to an increase in IL-2-mediated induction of c-Myc promoter activation indicating that it potentiates cytokine receptor signaling.
Pandey
A
A
Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA.
Fernandez
M M
MM
Steen
H
H
Blagoev
B
B
Nielsen
M M
MM
Roche
S
S
Mann
M
M
Lodish
H F
HF
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D002460:Cell Line; D016207:Cytokines / Q000494:pharmacology; D056827:Endosomal Sorting Complexes Required for Transport; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000502:physiology*; D016259:Genes, myc; D006133:Growth Substances / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism*; D019000:Phosphotyrosine / Q000032:analysis / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D018121:Receptors, Cytokine / Q000502:physiology; D017978:Receptors, Growth Factor / Q000502:physiology; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000502:physiology*; D014443:Tyrosine
D048868:Adaptor Proteins, Signal Transducing; D016207:Cytokines; D056827:Endosomal Sorting Complexes Required for Transport; D006133:Growth Substances; D007377:Interleukin-3; D010750:Phosphoproteins; D020033:Protein Isoforms; D018121:Receptors, Cytokine; D017978:Receptors, Growth Factor; D011994:Recombinant Proteins; C109775:STAM protein, human; C491647:STAM2 protein, human; D019000:Phosphotyrosine; D014443:Tyrosine; D004815:Epidermal Growth Factor; D066246:ErbB Receptors