FIGURE 4.

Sec22 homodimers are associated with Bos1. Washed semi-intact cells expressing Sec22HA in CBY740 and Sec22HA(D153C) in CBY773 were incubated in the absence (−) or presence (+) of 0.2 mm Cu²⁺/phen. After quenching reactions with NEM, membranes were solubilized with Triton X-100. Total solubilized extracts (T) and anti-Bos1 immunoprecipitates (IP) were resolved by non-reducing SDS-PAGE and immunoblotted for the indicated proteins. Total lanes represent 1/20 of the solubilized extracts loaded in the IP lanes. Yif1 is an integral membrane ER/Golgi protein and serves as a specificity control for the IP. Note recovery of the Sec22HA homodimer after cross-linking the D153C variant and IP with anti-Bos1 (far right lane).