Fig. 4. The peroxisomally targeted PEX26 fragments are inserted into the peroxisomal membrane. Human skin fibroblasts expressing GFP fusions of PEX26_2-305, PEX26_245-305, or PEX26_275-305-ALDP_87-164 were lysed in hypotonic buffer and membranes were separated from soluble proteins (S_Hyp) by centrifugation at 100,000 g. Membranes were then extracted with alkaline sodium carbonate buffer and again subjected to centrifugation to obtain a soluble fraction (S_Carb) and a membrane pellet fraction (P_Carb). Sample volumes were adjusted to that of the whole lysate (Lys) and each fraction was analysed by immunoblotting using antibodies against GFP, the integral PMP PEX14, and the soluble peroxisomal matrix enzyme catalase.