Spleen tyrosine kinase Adenovirus (Ad-Syk)

Syk p72 and ZAP-70 resemble the Src family protein tyrosine kinases in that they have a C-terminal catalytic domain, but differ in that they are characterized by two SH2 domains but no SH3 domains. Syk p72 kinase fused to the transmembrane and extracellular domains of CD7 and CD16, respectively, can induce complete T cell activation, implying the involvement of the Syk/ZAP family proteins in T cell activation. In contrast, the ZAP-70 kinase is insufficient for complete T cell activation unless it is coaggregated with a Fyn p59-containing chimera, suggesting that regulation of ZAP-70 activity may require a functional interaction with Src family kinases.