Figure 4. Surface-accessible residues in TMD0^TAP1.

(A) Single-cysteine mutants of TMD0^TAP1 vary in their tendency to form dimers. All 16 cysteine mutations are summarized in Table 1 and Figure S2. (B) Decrease in dimer formation in the presence of tapasin. Membranes were prepared from transiently transfected M553 cells, treated with CuP (+), PBS (−), or DTT and subsequently subjected to non-reducing SDS-PAGE and immunoblotting. An empty lane separates the oxidized and reduced sample.