Fig. 2. Purification of His₆-CAP1. HEK293 cells were transfected with pUSH-CAP1. The cell lysate was prepared (lane 2), and His₆-CAP1 was successively enriched upon a Ni²⁺-NTA- (lane 3) and a SP-Sepharose column (lane 4). Although gel filtration through a Superdex 200 column could not separate bound G-actin from His₆-CAP1 (lane 5), bound actin was liberated by treating the Ni²⁺-column-bound His₆-CAP1-actin complex with urea. Pure His₆-CAP1 was then eluted with imidazole after the urea was removed (lane 6). Molecular size standards were run on lane 1.