A model of the ARF-dependent activation of phospholipase D, and a proposed scheme for vesicle endocytosis. In this model, ARF activates phospholipase D (PLD), recruiting it to the plasma membrane. Hydrolysis of phosphatidylcholine (PC) by ARF-activated PLD produces phosphatidic acid (PA). PA subsequently recruits molecules that shape the inner face of the lipid bilayer, facilitating vesicle formation. Local enrichment of acidic phospholipids help recruit adaptor proteins (AP) and coat proteins (CP) to the membrane, initiating the budding of the vesicle. Vesicle fission is ultimately mediated by dynamin, which itself is a downstream effector of PA.