Table 1.

NEDD4 family E3 ligases.

Name	Full/alternate names	Regulation of GPCRs	References
NEDD4-1 (NEDD4)	Neural precursor cell expressed developmentally down-regulated protein 4-1	Lysosomal degradation	Shenoy et al., 2008, 2009; Berthouze et al., 2009;
NEDD4-2 (NEDD4L)	Neural precursor cell expressed developmentally down-regulated protein 4-2	Promotes p38 activation	Wolfe et al., 2007; Chen et al., 2011; Dores et al., 2012, 2015; Grimsey et al., 2015
	Neural precursor cell expressed, developmentally down-regulated 4-Like, E3 ubiquitin protein ligase
WWP1 (AIP5)	WW domain-containing E3 ubiquitin protein ligase 1 or Atrophin-1-Interacting Protein 5	Not yet known to regulate GPCRs	N.D.
WWP2 (AIP2)	WW domain-containing E3 ubiquitin protein ligase 2 or Atrophin-1-Interacting Protein 2	Proteasomal degradation	Oo et al., 2007, 2011; Dores et al., 2012, 2015
SMURF1	SMAD Specific E3 ubiquitin protein ligase 1	Not yet known to regulate GPCRs	N.D.
	HECT-Type E3 ubiquitin transferase SMURF1
SMURF2	SMAD Specific E3 ubiquitin protein ligase 2	Clathrin-coated vesicle mobilization	Groer et al., 2011; He et al., 2011; Henry et al., 2011, 2012
	HECT-Type E3 ubiquitin transferase SMURF2
NEDL1 (HECW1)	Nedd4-Like E3 Ubiquitin-protein ligase 1	Not yet known to regulate GPCRs	N.D.
	HECT, C2 And WW domain-containing protein 1
NEDL2 (HECW2)	Nedd4-Like E3 ubiquitin-protein ligase 2	Not yet known to regulate GPCRs	N.D.
	HECT, C2 and WW domain-containing protein 2
AIP4 (ITCH)	Atrophin-1-interacting protein 4 Or Itch E3 ubiquitin protein ligase	Lysosomal Degradation/Proteolytic Processing in MVBs	Abagyan and Totrov, 1994; Marchese and Benovic, 2001; Tanowitz and Von Zastrow, 2002; Marchese et al., 2003; Bhandari et al., 2007; Hislop et al., 2009; Mines et al., 2009; Berlin et al., 2010; Malik and Marchese, 2010; Henry et al., 2011, 2012

A list of the nine NEDD4 family members and their respective roles in GPCR functions.