Fig. 8.

PI4K2A and PtdIns4P regulate VAMP3 sorting. Following VAMP3 endocytosis at the PtdIns(4,5)P₂-rich plasma membrane subdomains (blue), VAMP3 passes through early endosomal compartments containing PtdIns(3)P (orange), prior to delivery to sorting endosomes enriched with PtdIns(4)P (brown). Availability of PI4K2A for interaction with VAMP3, along with the catalytic activity of PI4K2A, ensures proper sorting of VAMP3 within this compartment, a process that is a prerequisite for efficient interaction of VAMP3 with cognate Q-SNAREs, such as Vti1a, on target membranes.