FIG. 8.

A chimeric US6 inhibits peptide translocation and ATP binding by TAP. (A) Analysis of the effect of CCMV and chimeric US6 on peptide translocation by TAP. SLO-permeabilized cells were incubated with the fluorescein-labeled peptide at 37°C for 10 min in the absence (−) and presence (+) of ATP. The reaction was stopped by the addition of ice cold 1% Triton X-100. Translocation into the ER was quantified by measuring the recovery of glycosylated fluorescein-labeled peptides on agarose containing concanavalin A. AFU, arbitrary fluorescence units. (B) Analysis of the effect of the CCMV US6 and chimeric US6 on ATP binding by TAP. Cell lysates were incubated with ATP-agarose, and bound proteins were eluted and resolved by SDS-PAGE. Proteins were transferred onto PVDF membranes and probed with a TAP1-specific antibody.