N4WBP5, a Potential Target for Ubiquitination by the Nedd4 Family of Proteins, Is a Novel Golgi-associated Protein

Abstract

Nedd4 belongs to a family of ubiquitin-protein ligases that is characterized by 2-4 WW domains, a carboxylterminal Hect (homologous to E6-AP Carboxyl terminus)-domain and in most cases an amino-terminal C2 domain. We had previously identified a series of proteins that associates with the WW domains of Nedd4. In this paper, we demonstrate that one of the Nedd4-binding proteins, N4WBP5, belongs to a small group of evolutionarily conserved proteins with three transmembrane domains. N4WBP5 binds Nedd4 WW domains via the two PPXY motifs present in the amino terminus of the protein. In addition to Nedd4, N4WBP5 can interact with the WW domains of a number of Nedd4 family members and is ubiquitinated. Endogenous N4WBP5 localizes to the Golgi complex. Ectopic expression of the protein disrupts the structure of the Golgi, suggesting that N4WBP5 forms part of a family of integral Golgi membrane proteins. Based on previous observations in yeast, we propose that N4WBP5 may act as an adaptor for Nedd4-like proteins and their putative targets to control ubiquitin-dependent protein sorting and trafficking.

Drosophila Ndfip is a novel regulator of Notch signaling

“…15 Throughout Drosophila development dNdfip is expressed at low levels (both RNA and protein) with highest levels observed from pupariation through to adulthood (data not shown). Like its mammalian counterparts, 15,17 dNdfip showed significant colocalization with Rab7 in late PY1 PY1 TM1 TM3 TM2 TM1 TM3 TM2 Ndfip1/ dNdfip interacts with all three Drosophila Nedd4 family E3 ubiquitin ligases. As mammalian Ndfips interact with multiple E3s, we tested whether dNdfip binds the Drosophila Nedd4 family E3s dNedd4, Su(dx) and dSmurf.…”

“…Sequence comparison using Ndfip1 and Ndfip2 indicate that CG32177 encodes the only likely Ndfip homolog in Drosophila. 15 Similar to Ndfip1 and Ndfip2, dNdfip contains an N-terminal portion that harbors three proline-rich motifs indicating a potential for binding WW-domain proteins, three transmembrane domains and a short C-terminal tail (Figure 1a). 15 Throughout Drosophila development dNdfip is expressed at low levels (both RNA and protein) with highest levels observed from pupariation through to adulthood (data not shown).…”

“…15 Similar to Ndfip1 and Ndfip2, dNdfip contains an N-terminal portion that harbors three proline-rich motifs indicating a potential for binding WW-domain proteins, three transmembrane domains and a short C-terminal tail (Figure 1a). 15 Throughout Drosophila development dNdfip is expressed at low levels (both RNA and protein) with highest levels observed from pupariation through to adulthood (data not shown). Like its mammalian counterparts, 15,17 dNdfip showed significant colocalization with Rab7 in late PY1 PY1 TM1 TM3 TM2 TM1 TM3 TM2 Ndfip1/ dNdfip interacts with all three Drosophila Nedd4 family E3 ubiquitin ligases.…”

“…14 Both Ndfip1 and 2 are ubiquitously expressed proteins with three transmembrane domains, and interact with several Nedd4 family members through PY motifs. [15][16][17] Ndfip1 and 2 localize to Golgi, late endosomes and other vesicles and function as adapters and activators to facilitate the ubiquitination and regulation of a number of substrates. 15,[17][18][19][20][21] Here, we report on the Drosophila Nedd4 family interacting protein (dNdfip) homolog, and reveal that it is a novel regulator of Notch signaling.…”

Ndfip1 Regulates Itch Ligase Activity and Airway Inflammation via UbcH7

“…It is composed of three highly conserved transmembrane domains and cytoplasmic PY motifs, and it is localized to the Golgi, endosomes, and multivesicular bodies (10). Ndfip1 also was shown to interact with Itch.…”