Mixed disulfides of Tim13-Mia40 and Mia40-Erv1 were detected in the presence of Tim13, Mia40, and Erv1. Equimolar amounts of recombinant Mia40, Erv1 and reduced Tim13 were incubated together for 10 min followed by treatment with IAA. The mix was separated on reducing (A) and nonreducing (B) SDS gels. Proteins were detected by immunoblotting with specific antibodies. As a control, a lane with the single protein is included. The asterisk denotes multimers of Tim13, the diamond marks a dimer of Mia40, and the square marks a dimer of Erv1.