Figure 2. The partially oxidized form of non-secreted κ LC in P3U.1 cells is ubiquitinated.
(A) Cell lysates from P3U.1 cells treated in the presence or absence of lactacystin for 6 hr were immunoprecipitated with anti-κ LC antibody, and SDS-PAGE separation was performed under reducing or non-reducing conditions, followed by immunoblot analysis. The three different folding forms of the NS1 κ LC were detected (red, a completely reduced form, ox1 and ox2) in the top panel. In the bottom panel the ubiquitinated forms of LC are shown and the unmodified NS1 LC, which are also detected by the secondary antibody (goat anti-mouse Ig), are indicated with asterisks. (B) The same immunoprecipitated samples as in (A) were analyzed by 2-dimentional SDS-PAGE, followed by immunoblotting with the indicated antibodies.