※ Syk family introduction

    Syk (Spleen tyrosine kinase) belong to tyrosine protein kinase. Two members have been found in human genome, Syk and ZAP70. Syks contain two SRC homology 2 (SH2) domains and a C-terminal tyrosine kinase domain. Syks is intact catalytic inactive, and can be activated after binding of SH2 domains to phosphorylated ITAMs, or phosphorylation of tyrosine residues in linker regions. Syk is involved in integrin mediated signaling pathway and activated by integrins, active Syk is essential for firm leukocyte adhesion to the inflamed endothilium and development of MAC1-dependent vasculopathy reaction. Syk is also involved in innate pathogen recognition, including recognition of fungi, inflammasome activation, recognition of bacteria and viruses, signaling tissue damage and other immune functions. In addition, Syk act as a key molecule in regulation of bone metabolism, platelet functions, vascular development and other non-haematopoietic functions. Syk deficient or abnormal expressions will lead to some allergic or autoimmune diseases. What's more, Syk is also found to be required for the oncogenic activity of several viruses which can promote some virus-induced tumours development (1).

Reference
1. Mocsai, A., Ruland, J. and Tybulewicz, V.L. (2010) The SYK tyrosine kinase: a crucial player in diverse biological functions. Nat Rev Immunol, 10, 387-402. PMID: 20467426