GTPase-activating protein (GAP) for ADP ribosylation factor (ARF) (PubMed:19429787). Mediates clathrin-dependent trafficking of vacuolar cargo from the trans-Golgi network (TGN) (PubMed:23771894). Promotes plant growth (PubMed:23771894, PubMed:25763490). Involved in the regulation of membrane trafficking and cell separation during floral organ shedding and abscission (PubMed:19429787, PubMed:20081191, PubMed:20230490, PubMed:23963677). Prevents abscission zone (AZ) cells enlargement (PubMed:23963677, PubMed:25763490). Exhibits ARF-GTPase activity toward ARF1 at TGN (PubMed:21105926). Interacts with ARF1 at trans-Golgi network (TGN) (PubMed:21105926). Binds to clathrin heavy chain (PubMed:23771894). Colocalizes with AGD5 at the trans-Golgi network (TGN) (PubMed:21105926). Colocalizes with clathrin at the TGN (PubMed:23771894). Expressed in inflorescence stems, abscission zones, stigmas, roots, roots meristems, embryos, and floral and leaf vasculatures. Strongly expressed in developing and mature embryos. Abnormal vacuolar trafficking of soluble cargo proteins, and premature termination of the shoot apical meristem and of floral meristems leading to short siliques and abscission defect (PubMed:23771894, PubMed:25763490). Plant missing both AGD5 and MTV1 are severely dwarfed and have altered subcellular distribution of clathrin-coated vesicle (CCV) cargo exported from the trans-Golgi network (TGN) (PubMed:23771894). Floral organs remain attached to the plant body after the shedding of mature seeds, including abnormal petal breakstrength (pBS) (PubMed:23963677, PubMed:19429787, PubMed:20081191, PubMed:20230490). Ectopic enlargement of abscission zone (AZ) cells during shedding (PubMed:23963677). Impaired floral organ shedding associated with defects in the structure of the Golgi apparatus and extensive accumulation of vesicles adjacent to the cell walls in abscission zone regions (PubMed:19429787, PubMed:20081191, PubMed:20230490). Rescued by SOBIR1/EVR disruption, leading to premature shedding of floral organs and enlarge abscission zones (PubMed:20081191). Rescued by SERK1 disruption, leading to normal Golgi apparatus and endosome, as well as correct floral organ shedding (PubMed:20230490).