Two-step purification of cys-less arrestin-1 eNCL (C63V, C128S, C143V) (Hanson et al., 2006b; Vishnivetskiy et al., 2010). Coomassie gels for heparin-Sepharose (left panels) and subsequent Q-Sepharose (right panels) are shown. M, molecular weight markers; S, protein precipitated by ammonium sulfate and then dissolved and loaded onto heparin-Sepharose; Pt, pass-through; W, wash; H, pooled fractions from heparin-Sepharose; fraction numbers are shown (numbers greater than 40 after heparin and greater than 30 after Q indicate high-salt wash).