FCGR activation

Cross-linking of FCGRs with IgG coated immune complexes results in tyrosine phosphorylation of the immuno tyrosine activation motif (ITAMs) of the rececptor by membrane-bound tyrosine kinases of the SRC family. The phosphorylated ITAM tyrosines serve as docking sites for Src homology 2 (SH2) domain-containing SYK kinase. Recruitment and activation of SYK is critical for FCGR-mediated signaling in phagocytosis, but the exact role of SYK in this process is unclear. Activated SYK then transmits downstream signals leading to actin polymerization and particle internalization.

FcγR与IgG包被的免疫复合物交联，导致受体膜结合型Src家族酪氨酸激酶对免疫酪氨酸激活基序（ITAMs）进行酪氨酸磷酸化。磷酸化的ITAM酪氨酸充当Src同源2（SH2）结构域含有SYK激酶的结合位点。SYK的募集和激活对于吞噬作用中FcγR介导的信号传导至关重要，但SYK在此过程中的确切作用尚不明确。激活后的SYK进而传递下游信号，导致肌动蛋白聚合和颗粒内化。