(C) Mitochondria from the indicated yeast strains (wild type, pex19Δ, pex19Δmsp1Δ), expressing Pex13-V5 (under its endogenous promotor) were either left untreated (lane 1,2,3) or exposed to Na2CO3 and separated into the membrane pellet (4,5,6) or supernatant fraction (7,8,9). After separation by SDS-PAGE the fractions were immunoblotted for Pex13-V5 (α-V5) and porin (α-porin). 