NDFIP2 is a transmembrane adaptor protein that activates HECT domain-containing E3 ubiquitin ligases (ITCH, NEDD4, NEDD4L, SMURF2, WWP1, WWP2) through polyproline-tyrosine (PY) motifs in its N-terminal cytoplasmic domain 1. The protein localizes to the Golgi, trans-Golgi network, multivesicular bodies, and endosomal membranes, where it recruits E3 ligases to facilitate ubiquitination of membrane protein targets 2. NDFIP2 negatively regulates multiple cellular processes by modulating substrate stability; notably, it promotes ubiquitination-dependent internalization and degradation of aquaporin-2 (AQP2) 3, connexin43 1, and KCNH2 potassium channels. NDFIP2 also modulates EGF receptor signaling by controlling ubiquitination of PTEN and Src family kinases 4. The protein is rapidly degraded in lysosomes with a half-life of approximately 1.5 hours 1. Genetically, NDFIP2 variants are associated with blood pressure regulation through influence on renal sodium reabsorption via ENaC/NEDD4L pathways 5, and genome-wide association studies implicate NDFIP2 in tic disorder susceptibility 6. These functions position NDFIP2 as a critical regulatory hub coordinating E3 ligase-mediated protein degradation across multiple physiological systems.