FIGURE 7.

Cysteines positioned in the Sec22-transmembrane domain and luminal C terminus form disulfide cross-linked homodimers. Washed semi-intact cells expressing the indicated cysteine derivatives of (A) Sec22 or (B) Sec22 and Sec22HA in CBY773 were incubated in the absence (−) or presence (+) of 0.2 mm Cu²⁺/phen. After quenching reactions with NEM, proteins were resolved by non-reducing 10% SDS-PAGE and immunoblotted with anti-Sec22 or anti-HA. Arrows show the positions of monomeric and cross-linked forms of Sec22. The asterisk indicates a nonspecific cross-reactive species.