Table 1. Krz mutations used in this study, and their effects on viability.

Corresponding mutations in the mammalian orthologs were described in the following studies: phosphate sensor (KK/A) and phosphate binding (R/A) (Gimenez et al., 2012; Ostermaier et al., 2014; Shukla et al., 2013; Vishnivetskiy et al., 2000; Zhou et al., 2017), finger loop (VL/A) (Cahill et al., 2017; Hanson et al., 2006; Szczepek et al., 2014), phosphorylation-independent activated receptor binding (R/E) (Kovoor et al., 1999), clathrin binding (ΔLIQLD) (Kang et al., 2009; Krupnick et al., 1997), AP2 adaptor binding (F/A) (Edeling et al., 2006; Kim and Benovic, 2002).

Location in Krz	Mutant abbr.	Location in bovine visual arrestin-1 (SAG)	Location in human β-arrestin-1 (ARRB1)	Affected function	Rescue of zygotic lethality	Maternal/zygotic phenotype
K51, K52	KK/A	K14, K15	K10, K11	phosphate sensor	+	embryonic lethal
R66	R/A	R29	R25	phosphate binding	+	adult viable
V111, L112	VL/A	V74, M75	V70, L71	finger loop: receptor core binding	+	semi-lethal
R213	R/E	R175	R169	phosphorylation-independent activated receptor binding	+	adult viable
L454-D458	ΔLIQLD	N/A	L376-D380	clathrin binding	+	adult viable
F472	F/A	F380	F391	AP2 adaptor binding	+	adult viable
K51, K52, R66	KKR/A	K14, K15, R29	K10, K11, R25	double: phosphate sensor/binding	+	embryonic lethal
K51, K52, V111, L112	KKVL/A	K14, K15, V74, M75	K10, K11, V70, L71	double: phosphate sensor + finger loop	−	N/A
R66, V111, L112	RVL/A	R29, V74, M75	R25, V70, L71	double: phosphate sensor + finger loop	+/−	N/A