IDENTIFICATION OF A 4TH HALF ABC TRANSPORTER IN THE HUMAN PEROXISOMALMEMBRANE

Three half ATP-binding cassette transporters (ALDP, ALDR, PMP70) are k nown to be present in the human peroxisome membrane, Mutations in the gene encoding ALDP cause X-linked adrenoleukodystrophy; the role of AL DR and PMP70 in human disease is unclear. We report the cloning and ch aracterization of a fourth human gene encoding a peroxisomal half ABC transporter, The gene, designated P70R, maps to chromosome 14q24, enco des a 73 kDa transporter most similar to PMP70, and is expressed in al l human tissues examined. Because half ABC transporters heterodimerize to form functional transporters, the identification of a fourth membe r of this family in the peroxisome membrane has implications for our u nderstanding of mammalian peroxisomes and the genetic disorders of per oxisomal function.