Figure 2.

Arc residues 200–225 are required for the interaction with calnexin. Co-immunoprecipitations (IPs) were performed with a calnexin antibody and yellow fluorescent protein (YFP)-Arc deletion mutants. (A) Western blots probed with anti-GFP showed that full-length Arc (1–396) and Arc 101–240 bound to calnexin (left panel). Similar expression levels of YFP-Arc deletion mutants were confirmed by immunoblotting lysates with anti-GFP antibody (input, right panel). (B) To narrow down the binding region, co-IPs were repeated with progressive deletions of the Arc C-terminus. Arc 200–396 bound to calnexin while Arc 225–396 did not, indicating that Arc residues 200–225 are required for calnexin to interact (left panel). Equal loading was again ensured by immunoblotting equal amounts of lysates alone (input, right panel). (C) Alignment of the different Arc-deletion mutants. Numbers indicate amino acid positions. ± signs indicate positive or negative co-IPs with calnexin.