FIGURE 2.

The ERAD components Der1_Ap and Cdc48_Ap localize to the membrane compartment surrounding the apicoplast. Host cells infected with a transgenic T. gondii line expressing an HA-tagged version of Der1_Ap were fixed, frozen, and sectioned with a cryo-ultramicrotome. Sections were incubated with a rat antibody to HA (a, b, d, black arrowheads), a rabbit serum to ACP (9) (a and b, white arrowhead), and a newly developed rabbit antibody against recombinant Cdc48_Ap (c and d, white arrowhead with black outline, see also supplemental Fig. S1) followed by secondary antibody conjugated to 12 or 18 nm colloidal gold, stained with uranyl acetate/methylcellulose, and analyzed by transmission electron microscopy. Panel b shows a higher magnification of the cell shown in panel a, the four membranes of the apicoplast are indicated by black arrowheads outlined in white. Ap, apicoplast; Go, golgi; Nu, nucleus.