The peroxisomal membrane transport protein PMP34 mediates the exchange of adenine nucleotides between the cytosol and the peroxisomal matrix. The localization of PMP34 has been established by immunofluoresence studies (Wylin et al. 1998). The cloned human protein restores adenine nucleotide transport in yeast whose endogenous peroxisomal transporter has been disrupted, and has adenine nucleotide transport activity in reconstituted lipid vesicles in vitro (Visser et al. 2002), consistent with its hypothesized role in vivo (Wanders and Waterham 2006).