Distinct roles for Syk and ZAP-70 during early thymocyte development

Distinct roles for Syk and ZAP-70 during early thymocyte development

The spleen tyrosine kinase (Syk) and zeta-associated protein of 70 kD (ZAP-70) tyrosine kinases are both expressed during early thymocyte development, but their unique thymic functions have remained obscure. No specific role for Syk during beta-selection has been established, and no role has been described for ZAP-70 before positive selection. We show that Syk and ZAP-70 provide thymocytes with...

Differential Activation of the Tyrosine Kinases ZAP-70 and Syk After FcgRI Stimulation

Engagement of the high-affinity IgG Fc receptor (FcgRI) actiSyk nor MAP kinase activation was affected by the presence of ZAP-70. Although transduced ZAP-70 had in vitro kinase vates a signal transduction pathway involving tyrosine phosphorylation of associated kinases. We compared the activity and associated with FceRIg after receptor aggregation, it was not tyrosine phosphorylated. In contras...

Differential intrinsic enzymatic activity of Syk and Zap-70 protein-tyrosine kinases.

Syk and Zap-70 are related protein-tyrosine kinases implicated in antigen and Fc receptor signaling. While Zap-70 is restricted to T-cells and natural killer cells, Syk accumulates in B-cells, mast cells, platelets, and immature T-cells. In addition, we found that an isoform of Syk (SykB), which carries a 23-amino acid deletion in the "linker" region, is prominently expressed in bone marrow. To...

Differential Requirements for ZAP-70 in TCR

Distinct and cooperative roles of mammalian Vg1 homologs GDF1 and GDF3 during early embryonic development.

Vg1, a member of the TGF-beta superfamily of ligands, has been implicated in the induction of mesoderm, formation of primitive streak, and left-right patterning in Xenopus and chick embryos. In mice, GDF1 and GDF3 - two TGF-beta superfamily ligands that share high sequence identity with Vg1 - have been shown to independently mimic distinct aspects of Vg1's functions. However, the extent to whic...