Involved in the endosomal multivesicular bodies (MVB) pathway. MVBs contain intraluminal vesicles (ILVs) that are generated by invagination and scission from the limiting membrane of the endosome and are delivered to lysosomes enabling degradation of membrane proteins (By similarity). Thought to be a cofactor of SKD1/VPS4, which catalyzes the disassembly of membrane-associated ESCRT-III (PubMed:17468262). Target of pathogen-responsive mitogen-activated protein kinases (MPKs) that plays a critical role in plant basal resistance to Pseudomonas syringae in a SKD1-dependent manner by promoting multivesicular bodies (MVBs) trafficking upon plant infection (PubMed:25010425). Homodimer (PubMed:20663085, PubMed:25010425). Interacts with SKD1/VPS4, VPS60-1, CHMP1A and CHMP1B (PubMed:17468262, PubMed:19304934, PubMed:20663085). Binds to PROS/At4g24370 (PubMed:24385429, PubMed:25010425). Interacts with MPK6 and MPK3 (PubMed:25010425). Localized in multivesicular body when associated with SKD1. By Pseudomonas syringae pv. tomato strain DC3000 (PstDC3000). Phosphorylated by activated MPK6 and MPK3, this activation is required to trigger multivesicular bodies (MVBs) trafficking upon plant infection. No strong phenotypic alterations under normal growth conditions; slightly slow growth, slightly pale green and flat leaves, and reduced seed yields (PubMed:17468262, PubMed:25010425). Increased sensitivity to Pseudomonas syringae pv. tomato strain DC3000 (PstDC3000)(PubMed:25010425). Belongs to the VTA1 family.