Fig. 10. Model for HA signaling to GRC. After binding HA the HA receptor SorLA together with a postulated second receptor component (Rec) activates a pertussis-toxin sensitive heterotrimeric G protein (1), which interacts via PI3-K (2) with surface GRC (3) to induce Ca²⁺ influx (4). The increase in Ca²⁺ leads to activation of CaMK (5), which possibly together with PI3-K (?), triggers shuttling of more GRC molecules to the plasma membrane (6).