Fig. 5

Arrestin switch regions. a Conformations of the arrestin switch regions in the active form (orange (IP₆-activated arrestin-3 (Arr3)), magenta (phosphopeptide-activated arrestin-2; PDB 4JQI¹¹), cyan (rhodopsin-activated arrestin-1; (PDB 4ZWJ¹³)), yellow (p44; PDB 4J2Q¹⁰)) differ from those in basal arrestin-3 (gray, PDB 3P2D⁶). Insets highlight switch regions. In the inset showing aSwI, the sequences in four bovine arrestin isoforms are shown. b Quantitation of arrestin-3 binding to His₆-JNK3 in the presence and absence of IP₆ (100 µM), monitored using an in vitro pull-down assay. JNK3 was immobilized on Ni²⁺ resin, exposed to arrestin-3 (with disulfides stabilizing active or basal aSwIIb), washed, then eluted in sample buffer and visualized by SDS-PAGE and Western. Disulfide trapped arrestin-3 (red box) was quantified separately by densitometry and the ratio was calculated (means ± SEM). **p ≤ 0.01. The overall amount was normalized by the ratio of disulfide trapped arrestin (Supplementary Fig. 5)