Model of the role of FFAR2 in IAV entry into host cells. Upon initial binding with sialic acid on the cell surface, IAV binds to the FFAR2 protein, the C terminus of which is phosphorylated by the GRKs (i.e., GRK2, GRK5, or GRK6). β-Arrestin1 then translocates to the plasma membrane and interacts with FFAR2, followed by further interaction with AP2B1. Ultimately, the FFAR2–β-arrestin1–AP2B1 complex aids in the internalization of IAV via clathrin-mediated endocytosis.