Figure 5.

Guanine nucleotide-binding motifs are essential for CIITA activity. (A) G3A cells were cotransfected with the pDRA300CAT and pcDNA3 (lane 1), FLAG.CIITA8 (lane 2), or mutant CIITA (lanes 3 to 6). Cells were harvested 48 h later, and CAT activity was determined as described. The experiment was repeated three times. (B) Western blot to assess the level of protein expression by mutant CIITA genes (compare lane 1 and lanes 2–4; also compare lanes 5 and 6). An equal amount of total lysates was loaded, separated by SDS/PAGE, and transferred onto nitrocellulose. The blot was probed with the α-CIITA antibody. ns, Nonspecific band.