The NEDD4 (neural precursor cell expressed, developmentally down-regulated protein 4)-family interacting proteins (NDFIPs) are adaptor proteins that recruit NEDD4 E3 ligases to specific substrate proteins, which leads to the ubiquitylation and subsequent degradation of these proteins. They also act as activators of the E3 ligase activity by releasing NEDD4 ligase from its auto-inhibitory conformation. NDFIP1/2 have been shown to be involved in neural development by regulating the expression of the Robo1 receptor.
Jiyao W et al.(2023). "The conserved domain database in 2023.",