SLAP, a dimeric adapter protein, plays a functional role in T cell receptor signaling.
Engagement of the T cell antigen receptor (TCR) leads to rapid activation of protein tyrosine kinases, which in turn phosphorylate downstream enzymes and adapter proteins. Some adapter proteins, such as SLP-76, Vav, and LAT, positively regulate TCR-mediated signal transduction, whereas others, such as Cbl, play an inhibitory role. SLAP (Src-like adapter protein), an adapter protein containing a Src homology 3 and a Src homology 2 domain, was isolated from a yeast interacting screen by using N-terminal Cbl as bait. N-terminal Cbl interacts with SLAP in vivo and in vitro in a tyrosine phosphorylation-independent manner. We observed that SLAP is expressed in T cells, and upon TCR activation, SLAP interacts with ZAP-70, Syk, LAT, and TCRzeta chain in Jurkat T cells. In transiently transfected COS-7 cells, SLAP forms separate complexes with ZAP-70, Syk, and LAT through its Src homology 2 domain. Overexpression of a C-terminal-truncated SLAP mutant down-regulates nuclear factor of activated T cells-AP1 activity. We have evidence that SLAP forms homodimers through its C-terminal region. Serial truncations and mutations in the C terminus of SLAP demonstrate that there is a correlation between the loss of dimerization and the inhibition of nuclear factor of activated T cells-AP1 activity. The in vivo association of SLAP with key signaling molecules and its inhibition of T cell activation suggests that SLAP plays an important role in TCR-mediated signal transduction.
Tang
J
J
Department of Pediatric Oncology, Dana-Farber Cancer Institute and Department of Pediatrics, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA.
Sawasdikosol
S
S
Chang
J H
JH
Burakoff
S J
SJ
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D019281:Dimerization; D004792:Enzyme Precursors / Q000378:metabolism; D004926:Escherichia coli; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D019169:Jurkat Cells; D008565:Membrane Proteins / Q000502:physiology*; D010750:Phosphoproteins / Q000378:metabolism; D017354:Point Mutation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D012441:Saccharomyces cerevisiae; D015398:Signal Transduction; D000072377:Syk Kinase; D051746:ZAP-70 Protein-Tyrosine Kinase
D048868:Adaptor Proteins, Signal Transducing; D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell; C109742:SLMAP protein, human; C092947:SLP-76 signal Transducing adaptor proteins; C054979:antigen T cell receptor, zeta chain; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; D051746:ZAP-70 Protein-Tyrosine Kinase; C497261:ZAP70 protein, human