Research Progress on NK Cell Receptors and Their Signaling Pathways

Figure 2

Model of signaling pathways by NCRs. After binding to their ligand, NKp46 and NKp30 associate with the adaptors FcεRIγ and/or CD3ζ, while NKp44 binds to DAP12. Furthermore, ITAMs in the adaptor protein intracellular regions are phosphorylated by SFK. Phosphorylated ITAMs activate the tyrosine kinases Syk and/or ZAP70. This recruits and activates downstream molecules such as PLCγ, PI3K, and Vav1/2/3 with the help of LAT. PLCγ further causes Ca²⁺ influx. PI3K and Vav1 can recruit the small G protein Rac1 and activate the MAPK signaling pathway through cascade phosphorylation of the PAK1–MEK–Erk signaling pathway. In addition, the intracellular region of NKp44 contains an ITIM sequence that may be related to inhibitory signaling, but the specific mechanism is not yet clear.