Stonin2 (STON2) is a member of a conserved family of adaptor proteins that retrieve plasma-membrane localized synaptic vesicle proteins such as the synaptotagmin (SYT) family after synaptic vesicle release (reviewed in Maritzen et al, 2010). STON2 has a C-terminal mu homology domain that is 30% identical to that of AP-2, and interaction with SYT1 depends on this domain (Jung et al, 2007). STON2 also interacts with the AP2 complex through the STON2 WxxF motifs, and mutation of these residues abrogates SYT1 endocytosis (Walther et al, 2001; Walther et al, 2004; Diril et al, 2006). In addition, STON2 may also interact with other components of the emerging clathrin-coated pit, including EPS15 and ITSN1 (Martina et al, 2001; Rumpf et al, 2008). Although STON2 has been best studied in the context of SYT1 endocytosis, it also interacts with SYT2 and SYT9, and weakly with SYT8 and SYT11 (Diril et al, 2006). Mammalian cells contain another family member, STON1, which may also play a role in synaptic vesicle protein endocytosis, but its role and localization are not as well characterized.